All good points that I need to sort. Perhaps my answer would be that monogamy is an unrealistic, unobtainable goal for many and that is a product more a superimposed moral code than the reality of human desire. That only a very very few people are lucky enough to find someone who meets all their needs at all times throughout all stages of life. That everyone has their deal breakers, that each person must accept how much bad to accept to get the good, and where their line is.
Bullchit. If that's how you'd counsel your own son, I feel sorry for him. Raise your bar, man -- raise your bar!