Use 'Print preview' to check the number of pages and printer settings.
Print functionality varies between browsers.
Printable page generated Monday, 9 March 2026, 8:24 AM
2. Defining infidelity
2. Defining infidelity
When infidelity impacts us it usually feels incredibly personal so to make this course more alive – and to help you think about the application of theory and research to actual people – through this course you are going to be following a case study about a fictional couple, Oliver and Rhianna, who are married with a son and experiencing some issues in their relationship. Start by engaging in Activity 2.1.
Activity 2.1 Watch I-Spy episode 1
Please watch the first of five short films about Oliver and Rhianna.
Continue to Section 2.1 Sexual infidelity.
2.1 Sexual infidelity
One of the most obvious ways to define infidelity is in terms of sexual behaviour with a person other than that the committed partner. This might seem like quite a simple definition but as you will see it is potentially not so easy.
Defining infidelity in terms of sexual intercourse
One option is to define infidelity in terms of sexual intercourse. Yet, a closer look at the ways infidelity research operationalises sexual intercourse begs interesting questions. For example, in some of the biggest, random sample studies, infidelity prevalence is estimated by asking participants who are in a relationship how many people they had sexual intercourse with and coding sexual infidelity for any answer over one (e.g. Whisman and Synder, 2007; Leigh et al., 1993). The potential difficulties with this definition are myriad; it may lead to under-reporting if relationship partners are not having sexual intercourse with each other (but are with other people); in addition, the operationalisation clearly privileges a researcher-definition of infidelity over any definition that a couple themselves might have since this definition codes consensual non-monogamy (think ‘swingers’) as infidelity.
A more direct assessment of sexual infidelity involves asking respondents directly about experience of having sex with someone other than their primary partner (e.g. Træen et al., 2007). Doing this assumes that sexual terms such as ‘sex’ or ‘sexual intercourse’ are understood in the same way by all – however, research suggests this is a false assumption (e.g. Randall and Byers, 2003; Carpenter, 2001).
Activity 2.2 How do you define sexual intercourse?
Click on your preferred definition from the list below; once you have you will be able to see how your response compares with that of other people who have taken this course. (No one but you will know how you vote.)
Discussion
What specific behaviours ‘count’ as sexual intercourse is not – on reflection – straightforward. Some definitions exclude some types of couples (e.g. the first definition assumes a man and a woman while the second assumes that at least one of the people in bed has a penis).
There is also an issue of how narrow or broad the definition is with some people restricting sexual intercourse definitions to behaviours that involve ‘penetration’ of some sort. Solo sexual activities may not usually be seen as infidelity, but this too can depend on the context (e.g. if someone is masturbating while talking online to someone other than the partner).
Unsurprisingly infidelity research varies in how it defines the term ‘sexual intercourse’, with some random sample studies prioritising a ‘penetration’ definition and specifying anal and vaginal intercourse (Choi et al., 1994; Billy et al., 1993) and others just using the phrase ‘sexual intercourse,’ leaving respondents to decide what the term means to them (Whisman et al., 2007). In sum, although defining infidelity in terms of sexual intercourse may appear to be simple, on closer examination it is not.
2.2 Defining infidelity as sexual ‘activities’
A second way to define infidelity is in terms of a much broader category of sexual activities outside the committed relationship. Defining infidelity in this way results in higher estimates of prevalence. In eight nationally-representative American samples when infidelity was defined in terms of ‘sexual intercourse’ with someone other than the primary partner, the rate was found to be 1–4%; with ‘milder’ forms of sexual contact including kissing, and a mixed undergraduate and community sample, self-reported ‘cheating’ rates were 24–39% for men and 30–51% for women (Brand et al., 2007).
Research exploring what types of sexual behaviour is perceived as infidelity has found a variety of sexual behaviours may be so considered:
- masturbation in the presence of another
- oral sex
- sexual play
- ‘petting’
- kissing
- flirting
- visiting strip clubs
- pornography use.
(Randall and Byers, 2003; Whitty, 2003; Yarab et al., 1999; Roscoe et al., 1988).
The list of behaviours that may be considered sexual infidelity is growing ever longer. However, while broader definitions may be more inclusive, they may not be less controversial.
Infidelity vs. sex addiction
When considering how to define infidelity one question that can arise is what the distinction is between sexual infidelity and sex addiction. In our own research with Relate couple counsellors we found that some separated sex addiction – defined as ‘somebody who sleeps around because they need sex’ – from infidelity (Moller and Vossler, 2015) on the grounds that the motives were different. Of course, it is interesting to consider whether partners would make the same distinctions.
In any event one thing to note is that the construct of ‘sex addiction’ is controversial. One part of the debate hinges on whether feeling unable to control one’s sexual behaviour or engagement can be understood as having an ‘addiction’ to sex (Kraus et al., 2018). But criticism also comes from the fact that the label has been disproportionally handed to certain sexual minorities, in particular gay men; critics suggest that the label is thus used to stigmatise certain populations and sexual practices (Ley et al., 2014).
Pause for reflection
Take a moment to ponder the discussion about what sexual behaviours do or do not ‘count’ as infidelity. To what extent does this content shift or not shift your own understanding of infidelity?
2.3 Emotional infidelity
A second way to define infidelity is in terms of emotional intimacy with someone other than the committed partner. Consider this topic a bit more with the following activity.
Activity 2.3 What is worse – emotional or sexual infidelity?
Please think of a serious committed romantic relationship that you have had in the past, that you currently have, or that you would like to have. Imagine that you discover that the person whom you’ve been seriously involved with became interested in someone else. What would upset or distress you more? Select only one. If it does not feel comfortable to answer for your own perspective, think about answering from the perspective of a potential client.
Discussion
Rather than assuming that infidelity is only sexual, a broad body of research has explored both sexual and emotional infidelity. The most typical experimental paradigm comes from Buss et al. (1992) and involves a ‘forced choice paradigm’ such as the one above where participants have to choose the worst of two hypothetical scenarios (note that we amended this study paradigm as traditionally it only allows participants to select from ‘male’ and ‘female’ and thus accepts – or fails to question – traditional gender norms).
Evolutionary understandings of infidelity
Research on the response to hypothetical sexual/emotional infidelity arose from predictions in evolutionary psychology theory on gender differences in response to infidelity. The key proposal is that men will be more concerned by a female partner’s sexual infidelity and women by a male partner’s emotional infidelity (Harris, 2003; Buss et al., 1999). Research has explored this hypothesis in terms of:
- self-reported jealousy over hypothetical scenarios in various cultures (e.g., Buss et al., 1999)
- impact on attention and memory (e.g., Maner et al., 2009; Schutzwohl and Koch, 2004)
- physiological responses (e.g., Bendixen et al., 2015; Harris, 2000; Buss et al., 1992)
- relationship violence (e.g., Harris, 2003).
Debate continues over whether evidence exists for this evolutionary psychology hypothesis (e.g., Edlund, 2009; Buss, 2007; Harris, 2005). However the purpose of the current summary is first to point out how the field’s thinking on the definition of infidelity has been shaped by this considerable literature, and second that that this research field and the forced choice methodology originated by Buss (Buss et al., 1999), is based on the proposition that it is possible to separate sex and emotions.
Research has operationalised emotional infidelity in various rather vague ways, including ‘deep emotional attachment,’ and falling in love (Buss et al., 1999), feeling ‘deeply connected’ (Sabini and Silver, 2005), feeling connected and feeling love (Allen and Rhoades, 2008) and an investment of romantic love, time and attention to a person other than the primary partner (Shackelford et al., 2000). Behaviours that have been defined as emotional infidelity include: sharing intimate details, discussing complaints about the primary partner and meeting for an alcoholic drink (Luo et al., 2010; Henline et al., 2007), a list of activities that may suggest most friendships are adulterous.
2.4 Infidelity as secrecy and betrayal
A final way that the literature defines infidelity is on the one hand, in terms of secrecy of behaviour and on the other hand, experience of betrayal by the other partner. There is research support for this definition (e.g. Luo et al., 2010; Hertlein and Piercy, 2008; Henline et al., 2007) but defining infidelity in this way moves away from a behavioural operationalisation of the construct; in theory any behaviour that is kept secret or evokes a sense of betrayal can be defined as infidelity.
An even more broad definition of infidelity is also found in the literature, in terms of behaviours which break a couple’s contract, violate couple norms or contravene assumptions about relationship exclusivity (Hertlein et al., 2005; Boekhout et al., 2003; Drigotas et al., 1999). As Hertlein et al. (2005) point out, these broad definitions make it quite likely relationship partners will disagree whether one of them has engaged in infidelity, which underlines the tension between useful breadth of definition and problematic lack of precision.
Activity 2.4 Making sense of infidelity definitions
For the following activity, consider the following questions:
2.5 Internet infidelity
This next section focusses on a particular type of infidelity – that which occurs online or is mediated through social media or other digital technologies. This is an emerging topic for research that can be understood potentially as an example of the broader impact of digital technologies on all of us.
Consider these newspaper and magazine headlines:
- Adulterous WhatsApp messages cited in nearly half of Italian divorces
- Facebook cited in a THIRD of all divorce cases
- Divorce Lawyer: Facebook Is a Cheating Machine
These headlines suggest that our use of social media and other digital technologies are intertwined with our relationship behaviours; in all three cases the headlines allude to the fact that divorce lawyers increasingly examine social networking sites for evidence of infidelity and the third article also argues that social media use increases the likelihood of relationship breakdown.
But what exactly is ‘internet infidelity’? Do the following activity to see what counts as crossing the line for you online.
Activity 2.5 Online Activity and Behaviour Checklist
How likely do you think you would be to define these online behaviours as infidelity?
[Response key = 5-point Likert Scale for each activity in the list where 1 = ‘Definitely not infidelity’ and 5 = ‘Definitely infidelity’]
How do you score compared with our sample (N=160)? Note that if you score differently this does not mean your views are wrong – the numbers you are seeing are the average response for our sample and there was a range of responses across the sample as the standard deviation (SD) indicates.
Discussion
When you look at the results of a questionnaire remember that you must think about its validity and reliability. The Online Activity and Behaviour Checklist (OABCL) was developed by us and while it builds on prior research – especially the list of nominations of ‘unfaithful’ online behaviours by participants in Henline et al.’s (2007) study – it is not yet validated in another study and we have not statistically investigated the factor structure of the questionnaire (this is a statistical method to examine if a questionnaire is working as expected). The un-tried nature of our survey necessarily qualifies what we (or anyone else) can take from the results. Also – and this is important – in our study the average responses above come from a sample where everyone reported personal experience of infidelity. How do you think that this might influence the results?
It is important to note the potential limitations to your/our data but it is also worth thinking about the extent to which the findings echo the earlier discussion about definitions of infidelity – for example sexual behaviours with someone else online is highly likely to be defined as infidelity by this sample but looking at pornography is not. Broadly speaking, they seem less distressed by potential emotional infidelity behaviours – though this is not the case across the board.
2.6 General public and practitioner definitions
Clearly a variety of potentially competing definitions of infidelity have been proposed in the theoretical literature on infidelity; in trying to resolve which definition might be ‘best’ it is worth looking at the research on what people say about how they themselves define infidelity. There are not a lot of studies and some are reliant on hypothetical infidelity scenarios (e.g. Yarab et al., 1999) or begin with a pre-set list of behaviours rather than allowing respondents themselves to nominate what constitutes infidelity.
Only a handful of studies have utilised qualitative methodologies to explore definitions of infidelity (e.g. Hertlein and Piercy, 2008; Henline et al., 2007; Mileham, 2007; Whitty, 2005) and of these only one asked respondents about their own experiences of infidelity (versus asking about infidelity in general). For this reason, we decided to do a small-scale qualitative study exploring how seven couple counsellors define infidelity (Moller and Vossler, 2015).
We picked this group in part because we thought that they were likely to have experience through their work with lots of different types of definitions. A key suggestion in this paper was that the evidence of multiple contradictory definitions of infidelity provides evidence that the meaning/definition of infidelity is socially constructed. What this means for counsellors and psychotherapists working with infidelity is further explained in an extract from the paper below.
Activity 2.6 Reading an extract from Moller and Vossler, 2015
The presence of multiple conflicting definitions is consistent with the idea of infidelity as socially constructed (Carpenter, 2001), which in turns shifts consideration of infidelity from something that exists ‘out there’ (and can be charted/defined) to something that individuals construct rhetorically.
This view of infidelity would be congruent with the recognition that individuals flexibly use socially normative definitions of infidelity to present and understand their own and partner behaviour (Edwards, 1995). It also explains how one person is able to reject charges of infidelity by claiming that extra-dyadic activity was ‘just sex’ and another to deny infidelity on the grounds that there was no sex. This understanding suggests that partners use different definitions of infidelity in the context of couple counselling to negotiate blame and accountability and to assign or refute moral responsibility for solving the couple problem (Edwards, 1999).
A social constructionist view of infidelity supports the idea of eye-of-the-beholder definitions of infidelity, with the advantage that no one is excluded and no definition is privileged over another. A number of practitioner-theorists propound this relativist definition of infidelity for therapeutic work with couples (e.g., Hertlein and Weeks, 2007; Whisman and Wagers, 2005) and emphasise the importance of considering the idiosyncratic meanings of affairs (Levine, 1998). Such an approach appreciates all perspectives as valid within some particular context and can help counsellors to maintain a curious yet impartial and empathic position towards both partners (Reibstein,2013).
In contrast with researchers, for whom the issue of definitions has considerable relevance, this suggests that for practitioners the focus is not on the ultimate definition or ‘true’ meaning of infidelity but on the impact of different possible perspectives and their usefulness for the couple (Levine, 2005). A social constructionist systemic perspective (McNamee and Gergen, 1992) also implies that the counsellor in couple counselling is inevitably part of the rhetorical environment.
Practitioners should therefore accept the idea that they have a role in co-constructing definitions of infidelity with couples. Potentially this could involve challenging partner definitions as well as owning the influence of their own context (history, culture, training) on how they, as couple counsellors, think about infidelity.
From your understanding what might be the relevance of accepting the idea that infidelity is socially constructed for your work as a counsellor or psychotherapist?
Discussion
This understanding of infidelity potentially helps a counsellor/psychotherapist to move away from the idea that there is one understanding of infidelity and to more fully accept the varied ways that their clients define the term, including when these definitions are potentially contradictory. It potentially also helps them to understand that clients will use different definitions of infidelity in their relationships to defend themselves or accuse their partners.
2.7 Reflecting on personal meanings
The extract of the paper you read in Activity 2.6 suggested it is important that counsellors and psychotherapists consider how they themselves understand infidelity, and how their own social background and relationship and family history impacts their understanding. You have already been considering your own sense-making around infidelity; Activity 2.7 takes this a step further.
Activity 2.7 Self of therapist reflection
Our own values and personal limitations impact on the way we perceive and work with infidelity in therapy practice. Think about your values and feelings regarding infidelity in terms of the following different levels:
Having considered the various ways infidelity is defined it is now time to consider how infidelity is understood. This means considering infidelity theories which you will explore next in Topic 3 Understanding infidelity.