I often wonder if, in plenty of some cases, men cheat because they know that if/when the wife finishes it they will still see their children regularly if they want to but will have escaped the full-on hard work of raising them, and if they don't want to see them at all or irregularly, there's nothing a wife can do to prevent that. Nothing.
If you are a man in an unhappy marriage it's much easier mentally and emotionally I think, to find a new woman to move on to first, (because they are shit at going for too long without regular sex) cheat with her, safe in the knowledge that their hand will be forced when the wifey finds out (rather than having to face telling her himself he wants out with no new sexual partner lined up)...then he has to leave...but he can still see the kids and hey presto he has sex on tap, no full-time children and so can start having fun again too.
Simples.
AMAZON, you have it in one. Exactly why my XP does it, he is extremely happy with his life now. No real commitment to anyone, plays around with a couple of women a week, never lets them near his home as it's his area, doesn't have DD over night but does get to do the good days out with her, exciting stuff, when he'a had enough he brings her home to me.
Pays £350 per month for this privelidge and I get to be free from a controlling habitual cheat. YIPEEEEE!