I actually think the number is a lot higher than stats show because it’s a hard metric to baseline (most people won’t admit to it.) So for this analysis 🧐 I’m assuming an affair is not just emotional contact but physical of any kind. Just a quick google (out of pure morbid curiosity yields this;
Studies show that 20% to 40% of adults admit to having an affair at least once in their lives. However, because this relies on self-reported data, experts estimate the true rate of infidelity—including emotional affairs and one-night stands—could be closer to 40% to 50% across committed relationships.
However I posit that the true data is even higher. I would benchmark it as around 70% over the course of a long marriage - and this includes both sexes. Reason? Whilst societal views remain disapproving of extra-martial liaisons, the reality is most people (not all, most) are not engineered to be monogamous long term. Nature favours procreation over societal disapproval and we are hardwired to prioritise sex with suitable partners throughout our lives. This is why you often see the sexual trend of an older man running off with a younger woman. It’s primal programming in action.
Of course not everyone is a long term marriage has an affair, I’m not suggesting that. But I reckon a lot do. At different points in their marriages. I think it’s a sort of unspoken truth of the human condition that has been pushed underground by modern sensibilities and religious conformity.