we al may fetishize what it would be like, but from what I hear its a whole ass 2 jobs to make sure that everyone feels emotionally satisfied enough. Sex is one thing but if you have even one partner with a higher than average sex derive it could be a problem if they rely one the same partner to get that from.
Most stories i hear after years later, people change, at first they say they didint cate about marriage, but when older maybe they do. When sex becomes less important, geeping the fire alive is more important.
I havnet met many Poly relationships, but I never met a long lasting one