Approximately one third of people admit to having been unfaithful to their current or former partner.

The real figure is probably much higher – more than half (54%) of Americans say they’ve been cheated on in the past.

Men are about twice as likely to be unfaithful as women. This is very well-replicated, and holds irrespective of culture or geography.

Men are also more likely to say that certain types of physical intimacy – such as kissing, sending nude photos, or sexting – with another person should not be considered cheating (a fact which might drive up figures even further).

But what motivates us to become unfaithful? Can it be prevented? And how can we predict whether our partner is likely to cheat on us?

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Gender differences

To understand the motivations for infidelity, it’s important to understand a major gender difference. Research overwhelmingly finds that men are likely to be unfaithful for reasons related to sex, whereas women are likely to be unfaithful for reasons related to how valued they feel in a relationship, and other emotional factors.

Men are more likely to report being motivated by sexual desire, desire for variety, and situational forces, whereas women are more likely to report being motivated by neglect.

It isn't just sex, either: gender performance also plays a role. Stereotypically “masculine” men are more likely to betray their partners, conforming to the masculine ideal of being sexually prolific – whereas stereotypically “feminine” women are less likely to do so.

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Relationship factors

But gendered factors are not the only ones at play. Also relevant is the relationship itself: those in relationships for longer were found to be more likely to be unfaithful, although this is partly inevitable – longer relationships provide more opportunities to commit infidelity, as well as motivations in the form of monotony or boredom (particularly for men, who are more likely to seek sexual variety than women). 

Relationships that are high in open communication, meanwhile, are unsurprisingly less likely to give rise to infidelity. Individuals who felt they could talk openly with their partners were less likely to have cheated, as well as less likely to have been cheated on.

Interestingly, participants who reported that their partner had been unfaithful were more likely to identify trust as a problem in their relationship, but those who had cheated themselves were not more likely to do so – perhaps unaware of their partner’s ambivalence towards them.

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Individual factors

Even if your relationship is happy, if you yourself are not then infidelity becomes significantly more likely. People who exhibit depressive symptoms, or have low self-esteem, are both more likely to be unfaithful.

The same is true for people who show signs of narcissism, and those who have a low tolerance for frustration. In particular, those who believe that they are very attractive and have many romantic or sexual options are more likely to be unfaithful to their partners.

Neurotic people are also less likely to experience happiness in their relationships, more likely to be insecure, and more likely to behave impulsively – all of which contribute to infidelity.

There are also traits that make people less likely to be unfaithful. These include being high in agreeableness, which makes people less likely to react to relationship conflicts with anger. Very conscientious people are additionally more likely to believe that relationships require work and sacrifice, which lowers the likelihood that they’ll cheat on their partner when things go awry. (We’ve blogged previously about the risks associated with a “destiny mindset,” or the idea that relationships are either meant to be or doomed to fail.)

Individuals who have insecure, anxious, or avoidant attachment styles are also more likely to commit infidelity than those who are 'securely attached'.

Finally, a big individual variable in propensity to be unfaithful is something called sociosexual orientation. This roughly describes people who have permissive (rather than conservative) sexual attitudes, who are positively disposed towards casual sexual encounters, who are likely to have had a number of one-night stands previously, and likely to want more in their future.

People who score high on this scale are typically sexually assertive, flirtatious, and more easily turned on by situational sexual cues (i.e. being flirted with or being in close proximity to someone they find attractive). They’re more likely to see others in a sexual way, and less likely to be highly attentive, transparent, or nurturing towards other people, including partners. Men typically score (much) more highly on the sociosexuality scale than women, which helps account for the gender differences in both frequency of and motivation for unfaithfulness.

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The aftermath

As part of the research for this blog, we ran a survey aimed at people who’d previously been unfaithful to monogamous partners.

One of the clearest results to emerge was a split in responses between those who reported regretting their past infidelity and those who didn’t.

We’ve shown some of these in a graphic below.

Several respondents reported that their infidelity had made them realise they were in the wrong relationship, or that they weren’t ready to be in any kind of relationship – but others (exclusively men) shared that their infidelity had taken place from within a happy relationship, and that it was the result of yielding to situational temptation and not necessarily a source of discomfort or regret.

A good deal of research has gone into how people tend to feel after being unfaithful to their partners. Most people see themselves as being very loyal and faithful, and consider romantic infidelity to be a morally unacceptable behaviour. Yet a huge proportion of people also cheat on their partners.

Our minds struggle with discrepancies between what we think and what we do, and we experience cognitive dissonance (and emotional discomfort) as a result. When this happens, our brains try to minimise the pain – often by minimising our own responsibility or role in the action undertaken, for example by telling ourselves that we had no other choice, that our choice was justified, or that our behaviour wasn’t really that bad anyway.

One 1998 experiment asked spouses to describe a conflict they’d both experienced. The partners most responsible for the conflicts tended to describe the conflicts as less serious, and also more justifiable.

The same is true for people who are unfaithful: perpetrators tend to describe their infidelities as less consequential than the partners they hurt.

This makes it easier for us to be comfortable with ourselves, but can make it much harder for our partners to forgive us. There is another gender effect worth noting here: women who believe they’ve been unfaithful tend to feel significantly worse than men who believe the same thing.

Infidelity is a complicated phenomenon, but it’s not unusual. One striking fact was that in at least one of the experiments discussed above, unfaithfulness didn’t actually predict whether a couple was more likely to have broken up after a year. Perhaps a future focus of research should be the capacity of humans to understand and forgive each other.

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