I agree about compatibility in long term relationships just not that every relationship is either a hookup or on the marriage track. Maybe that wasn’t what you were implying but it struck me that way.
My mom was with the same man for 22 years after my dad died but they never married or even lived together although were committed partners. I just think that the “relationship escalator” can cause its own problems. I just had a twice married friend break up with her boyfriend of 8 months because she just assumed that’s where their relationship was heading and he was enjoying loving and committed connection for itself. Now if someone really desires to be married there is nothing wrong with that but I’m not even sure she knew what she actually wanted other than what she assumed was the right thing. It kept her from being present to what was actually there in her very good and enjoyable relationship.
I think that falling into this unconscious track is a big part of what kills intimacy and heat. It’s easy to start sleepwalking through your relationship because you are doing what you are supposed to do rather than what feels energizing or bonding.