Cheating is wrong and awful but there are probably other logical reasons in addition to the simplified "Men who make less money are less manly so they feel more manly by fucking women" argument...
Men who are 100% dependent on their spouses, so I suppose it's fair to suggest that they're not economically viable. This isn't just breadwinning, where one spouse makes more than the other, even if it's just a few thousand dollars, this is 100% financial dependence. So, arguably, wife makes enough money for both of them, so husband, arguably, stays home during the day.
Generally, if you don't go to work during the day, and you do things either around town, with the kids, like errands and so forth, you're going to notice that there are far more women at these events than men. Further, in the "working world" because of gender inequality, men who are at work more consistently are likely to be around more men... And this varies from industry to industry but it's still generally true that there are more working men and more non-working women.
So, I think this is a numbers game.
Men who are 100% dependent are not working.
If they are not working they are necessarily around fewer men.
If they are not working they are probably around more women in non-working situations.
Seems arguable at least.