I understand it, but it's sad. I have met lots of guys who try to do this but they eventually can't do it. In the long run, it's not fair to the guy, his wife or his kids.
Don't you know that emotional relationships without sexual attraction are the strongest. I have plenty of them. But instead of calling them my wife I just call them friends. Sometimes I will call them faghags if they're female. This guy just has a different name for them.
Also I think this is just a confusion of identity vs orientation. Plenty of straight guys(identity) are homosexual(orientation). Haven't you heard of the 40's and 50's before??? Being gay(as an identity) didn't really even exist until the late 40's.
Sure, plenty of straight (identity) guys are homosexual (orientation). It also leads to untold grief. What I'm saying is, I'm not buying a therapeutic approach that generally tries to reconcile the two within a straight married lifestyle, as in my experience that generally leads to unhappiness on the part of all.
Of course, I've heard of the 40s and 50s, youngster.
Being culturally gay didn't generally exist as an identity until fairly recently, but neither did openness or acceptance. We do not want to go back there.
You are young. You will learn. I know that sound annoying, but it is true in this case.
EDIT: I do think that if someone finds himself in this position that occasionally he can make an open marriage type of arrangement with his spouse, that works for both. The danger, of course, is that he will unintentionally come to find more emotional satisfaction in his outside sexual relationships.