Nobody likes to be cheated on. When researchers ask divorcees about their reasons for breaking up, infidelity always comes out on top. Whether married or not, when someone is unfaithful, a break-up often ensues – and the experience can be especially upsetting for the betrayed partner.
Studies show that being betrayed can increase the risk of becoming depressed, being diagnosed with clinical anxiety, and even suffering from PTSD. Infidelity in relationships also raises the risk of domestic violence.
Psychologists have characterised the experience as a form of ‘attachment injury’, much like the trauma a child experiences when they learn they can't trust the caregiver they've bonded to.
All of this confirms what you probably already knew – that, moral issues aside, infidelity might be best avoided, if we can help it.
However, according to an authoritative new review, there’s at least one major catch: few of us, including expert researchers, can agree on what counts as infidelity.
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What counts as cheating, according to science?
If you're in an exclusive romantic relationship with one person (rather than in a consensual non-monogamous or polyamorous relationship), take a moment to think about your own behaviour or your partner's and what you'd consider a form of cheating.
It starts easily enough – to most of us, having sexual intercourse with someone outside of the relationship is an obvious form of cheating. What about engaging in other forms of sexual contact with someone else, such as oral sex or touching of intimate areas? Again, most people would probably still think of this as cheating.
But what about just kissing? Only kissing on the cheek? Or holding hands? Dancing? Flirting? Sexting? What about if your partner simply provided tender, emotional support to another person of the same sex as you? What about if they looked at porn when you weren't around? Does any of that make them unfaithful?
Everyone probably has their own ideas about these things – and their views might even change over time or while in different relationships.
“Studies have widely shown that individuals frequently differ in their subjective understandings of ‘infidelity’, especially where sexual contact is not involved,” says Benjamin Warach, a clinical psychologist and infidelity researcher at Stony Brook University, USA and co-author of the review.
“Research [also] demonstrates that individuals often differ in their perceptions of what ‘sexual contact’ entails and does not entail.”
How common is cheating?
For their new review, Warach and his colleagues tracked down all the English-language research studies into rates of infidelity that they could find. “This study presents the most comprehensive picture to date of the current ‘state of affairs’ in peer-reviewed infidelity prevalence research,” they wrote.
It’s a large field. The team found 305 studies involving collectively over half a million participants. These participants were from 47 countries on six continents, which sounds impressive – but there are some huge biases in the literature, which already limits our scientific understanding of infidelity before getting to the problems defining it.
Just over half of all the participants were in North America and nearly 20 per cent in Europe. Most were ethnically white. What’s more, most of the research (over 95 per cent) involved heterosexual couples, with just one study with people in gay relationships and one involving bisexual people. There was also a bias toward married couples – around a quarter of the studies ignored other types of relationship.
When it comes to the critical question of how to define infidelity, the research is all over the place.
“The often idiosyncratic nature of individuals’ perceptions of infidelity highlights the need to properly define terms for study participants and to ask participants if they consider the behaviours in question to be forms of romantic betrayal,” says Warach.
“In our meta-analysis, we found that researchers frequently do not do either. This lack of fidelity to good research practices is a huge problem for our field.”
What is the most common type of infidelity?
The usual approach that psychologists studying infidelity take is to ask people to report on their own behaviours, but the questions they ask vary a lot. For example, around 30 per cent of studies simply asked people to say whether they've ever been ‘unfaithful’ or ‘cheated’ or ‘had an affair’ – essentially leaving the interpretation of such things down to the participants.
Meanwhile, just over half of all the studies have used descriptions of forms of sexual infidelity, around 10 per cent have focused on emotional infidelity and five per cent on electronic infidelity, such as sexting.
All this variability in the methods means the best estimate for the prevalence of cheating in relationships is far from straightforward. However, Warach’s team did come up with some figures.
For sexual infidelity, 17.45 per cent of people said they’d engaged in it, on average; for emotional infidelity it was 27.5 per cent. For non-sexual but potentially disloyal behaviours (such as dancing or holding hands with someone else), the figure was 35 per cent.
Readers might not be surprised that men admitted to a lot more infidelity than women, no matter how it was defined. For instance, 25 per cent of men admitted to sexual infidelity, compared with 14 per cent of women; and 35 per cent of men admitted to emotional infidelity compared with 29 per cent of women.
Even the way psychologists collected their data led to different results. When they interview people about whether they’ve ever been unfaithful, this leads to lower average estimates than when they’ve asked people fill out an anonymous survey, presumably because participants are more reluctant to disclose their infidelity in a face-to-face situation.
Setting the boundaries
Taking a big-picture view of all the research on infidelity reveals several facts: infidelity is widespread; infidelity is harmful to relationships and to the people who feel betrayed; there’s huge variation in what people perceive as infidelity (and there are seemingly ever more ways to potentially be unfaithful, thanks to the rise of social media and ubiquity of digital communication).
All of this presents a puzzle – how can we take steps to avoid a harmful situation that is so subjective? As with many matters to do with human relationships, a good place to start is with better communication.
“Romantic exclusivity remains the norm in romantic relationships and continues to be essential for the majority of individuals,” says Warach.
“Given that technology has made betraying one’s partner – and concealing having done so – easier than ever, romantic partners should be intentional about communicating their expectations of romantic fidelity and, for the majority that choose exclusivity, making good on their commitments.”
In other words, if you're invested in your romantic relationship and expect a degree of loyalty from your partner (and they expect it from you), it’s probably worth taking the time to chat through with them what you both consider to be cheating.
If you find that you have different ideas about it, it’s better to find out now, before events unfold and one of you ends up feeling hurt and betrayed. Aim, if you can, to reach a fair consensus on your expectations for the relationship so that both parties know where they stand.
Of course, you might both agree that it will be more realistic or enjoyable to allow each other a degree of freedom outside of the relationship – polyamorous relationships are on the increase. However, communication is still essential. Polyamory doesn't mean there are no boundaries, just that the boundaries are different, and it could still be helpful to talk about each other's expectations.
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