MB, are you saying that you think that Drifter's friend's husband is happier with her cheating on him than he would be if they were openly polyamorous? A sort of unspoken but understood, "I just don't want to know, just let me pretend it's not happening" sort of situation? How would you really know that your spouse felt that way if you were always hiding your affairs?
I suppose there is probably someone who likes that, but is that really the case in the majority of these situations? Like the OP and most of the men who are complaining about their lack of marital sex in this thread?
It seems like the vast majority of those situations would be one cowardly spouse who just wants to excuse his/her own behavior by deceiving her/himself that his/her spouse is happier with "secret" affairs than the alternative, trying to rekindle a sexual spark or honestly including a new sexual partner for the unfulfilled spouse.
I know a lot of people who have been cheated on, and I've been cheated on before, too, and I've never heard the cuckolded person say, "I was glad he/she kept it a secret from me." I've never heard anyone say, "I knew but I didn't want to know, you know?" I'm not saying that doesn't happen, I'm sure that it does, but a lot of people are cheated on and the end result is usually an unbelievable amount of pain and regret. I've seen that pain, and I've wondered how anyone could inflict that pain on anyone that he/she is supposed to love. It's always been cruel to me, to the person who is hurt, that pain.