SG says "While I think counselling might be helpful, choose your counsellor carefully as quite a few of them are basically monogamists and will spend all their time trying to 'cure' you of your resistance to monogamy. Which will be unhelpful bullshit."
I think that's very unfair and prob a great exaggeration- is it based on your own experience of counselling, or heresay?
I have many friends/colleagues who are counsellors and they would be horrified to hear themselves depicted in that way.
I am not replying so much to you SG here, as making a general point- most people do aspire to the "lasting relationship for life" ideal. I think if you did a straw poll, most people would say they wanted a loving relationship that lasted for a long time.
Unless both people who start off as a couple are feeling the same- that the relationship is only temporary- then one of them is going to get hurt.
I don't think it's fair to accuse people who conform to the couple "norm" as not having thought about the options- it's a bit patronising to accuse them of that.
I think most people acknowledge that no one person can give them 100% of what they would want-and most relationships unless you are REALLY lucky, involve some sort of compromise, but whether fleeting or short term relationship, or any other kind of relationships, make them any happier, is a debatable point.
It has been shown time after time that children thrive best in a 2-parent family which is stable; I don't believe you should stay together if the relationship is dire, but on the other hand I also think you have a responsibility to your child, who has, and needs, to see their father.
OP maybe you need to step outside of the here and now a bit and think about how you would like to see your life in 10 or 20 years time. It's easy to have temporary relationships in your youth, but do you still w ant to be alone or playing the field in your 60 and 70s?