Welcome to the forum.
I was hanging out on a physics website for a long time and stuck in many ways. There were just things that appeared impossible to fit into logic - inherent paradoxes in experience that defied precise description.
I spent a lot of time arguing with people who were well educated, but in many ways narrow minded (in my opinion at least).
I finally left that site in frustration (there were a few people that did see some similar things but much of the forum was just childish heckling) and went to another physics site where I had some rather life changing views presented and as I read your post, a lot of what you're saying is almost like reading a post I might have written myself
I'm in a bit of a rush and can't post much, but I enjoyed seeing your post and can relate to most everything in it, though you could still have a non-possessive monogamous relationship between people that simply didn't find something with anyone else, but yes a lot of (most?) monogamous relationships appear to be possessive, restrictive and not very much representative of a more ideal caring, loving relationship.
Oh, and just yesterday I was talking with someone about how a more ideal lifestyle is much like a dance also
.... the "problem" is that you can't really teach or predict all the dance steps, you've got to be open to learning new dance steps on occasion and try to keep things in balance.