Why People Who Cheat Are Still Not Cool with Being Cheated On

The study, published in Social Science Research, aimed to understand how often infidelity, or extradyadic sex (EDS), occurred among both heterosexual married and co-habiting couples in recent generations. To do that, the Penn State research team looked at data from the National Longitudinal Study of Adolescent to Adult Health, which followed a group of adolescents in 1994 into their 20s and 30s.

Researchers also wanted to find out if there were any consequential differences between being the cheater and being cheated on. "Knowing that your partner had an outside sexual relationship may not have the same consequences for relationship dissolution as the knowledge that you engaged in EDS," they write.

Overall, a quarter of married or co-habiting respondents said they or their partner, or both, had sex outside of their relationship. Men were more likely to self-report their EDS, while women were more likely than men to report a partner's.

Researchers also discovered that when comparing the numbers, many have figured out how to effectively cheat on their partners without their knowledge. "Estimates indicate that 10% of women report their own EDS, but close to half as many men (5%) report a partner's EDS," the authors write. "Similarly, 13% of men report their own EDS, but only 8% of women report a partner's EDS."

When a man or woman found out their partner was engaging in EDS, the study reports, they were more likely to dissolve the relationship than if they were the one doing the cheating or if they reported no infidelity. "People seem to prefer to play the cheater over the cheated on," Michelle Frisco, one of the study's authors, said in a news release.

Ironically, both male and female respondents said staying committed was important for a successful marriage or serious relationship. When asked to rate the importance of fidelity on the success of a marriage or longterm relationship on a scale of 1-10, the average rate reported by women was 9.84, and for men, it was 9.68.

Dr Jill McDevitt is the resident sexologist at Swiss Navy lubricants. After reading the research, she tells Broadly she's not surprised by the findings. The fact that men were more likely to report engaging in EDS supports what studies on past generations have also concluded, she says.

Also, the idea that a partner's EDS was more likely to be reported as contributing to relationship dissolution "is very much aligned with the actor-observer cognitive bias, in which people attribute other people's behaviors to their character as a person, but their own behaviors to mitigating circumstances," McDevitt explains. "So, this idea that 'if my partner cheated, it's because they're a terrible person and I can't be with them so the relationship is over,' but 'if I cheat, it's because they weren't available to me, and I was caught up in a moment, and it was one little mistake.'"

McDevitt points out that one limitation to the study was that because the researchers looked at existing data rather than do a new survey, the relationship between EDS and relationship dissolution is correlational, not causal. "It could be that EDS caused the relationship to fall apart," she says, "or it could be that an already crumbling relationship lead the unhappy partners to seek sexual intimacy elsewhere."

It's also important to note that the Penn State study doesn't suggest one in four people will cheat. "Respondents didn't say if they are in open relationships, engage in polyamory, swinging, sexual surrogacy through an illness or sexual dysfunction, or otherwise engaged in consensual extradydadic sex that doesn't constitute cheating or betrayal for that couple," McDevitt says.