The gap has been narrowing for decades on this. It started before the smartphone and social media. Smartphones and social media have helped women seeking infidelity in so-called monogamous relationships.
Men have more desire to cheat in a monogamous relationship but less opportunity to do so. Women have less desire but more opportunity.
I think the type of relationship matters too. I think there's a difference between cheating levels in marriages vs. non-marital relationships. In non-marital relationships, I think women might cheat slightly more because those are younger couples. However, it is possible that non-marital relationships break up before cheating can happen.
Cheating is a concept that is applicable in monogamous relationships. Non-monogamous relationship types are growing too and there's much less of an infidelity concept in those.
Male cheating is not equally distributed. The top tier men that commit to women cheat because they are top tier men with many options. Many top tier men are now not getting into committed, monogamous due to abundance mainly from swipe apps. There are some middle aged betas that cheat, usually using the power of a high salary in order to get some side action. Betas in relationships without money likely aren't cheating due to lacking the opportunity to do so.
