@PicsInRed
The problem isn't lack of monogamy, the problem is that so many of these people don't seek out others the same, they want a faithful spouse at home and to shag away on the side.
Often the thrill of the "trick", getting one over on the faithful spouse, is part of the fun for the cheater. That's why we name it "cheating", that's was makes it wrong, and that's what causes a feeling of betrayal and "heartbreak" in the faithful partner and damages their ability to trust again.
The cheater has deliberately defrauded a faithful person and they really aren't a decent person, can't be. If they were decent, they would leave first to release their spouse to find someone more compatible and/or they would date only those also shagging others.
Agree with all this. ^ You will also find people who do this don't like it when it's done to them either. I knew a man some years ago, who was always fucking different women (from work and his 'hobby' groups, he must have had 10 affairs in 20-25 years!)
His poor wife stayed with him, as she didn't have the confidence to leave, and they had 2 kids. When they had been married 27 years, she had an affair with a neighbour, and he was fuming, angry, furious, and INCENSED that she had an affair, because just how DARE she?!
He demanded she end it, and said if she doesn't he is leaving. She picked the neighbour. Packed up everything she had and moved in with him. 10 years later, she and the neighbour are still together.