Why do you confine your question to the subgroup of "happily-married men" rather than the larger overall population of "married men?"
To avoid the class of “men who marry unhappily when they are really homosexuals or pedophiles”.
I don’t believe that a man who is simply unhappy with the particular marriage he is in would be inclined to have pedophile gay sex. They might well go for adultery, or for divorce/remarriage.
So I was simply trying to find a shorthand to preclude from my question those who are naturally disposed to homosexual and/or gay pedophilic relationships, but have gotten married anyway because it is the “proper” thing to do, maybe to hide their homosexual or pedophilic tendencies.