With men it seems to be mostly a matter of discipline and commitment to either an ideal or to all-encompassing work which involves them so much they don't even think about being unfaithful.
Well, personally, my wife as my wife is the primary factor. If a man doesn't have discipline or commitment to an ideal or overwork, he'll stumble across it with a good woman.
That's why they say that love is nature's psychotherapy.
If a good man is married to a good woman whom he loves and who loves him and meets his intellectual and emotional needs as a wife---at least most of the time---he instinctively knows that the physical intimacy that he has with her can never be equaled by anyone else while they are both alive.
Trump of course, not ever having attained the basic ethical orientation of a "good man," has no such knowledge.
The rarely used standby second brain housed between their legs... It just has a self dis struct button that guys have yet to work out what its for ..its a push at their peril Thing.....:(D