I could have written your post verbatim.
I was in a relationship for a year and a half. We loved each other. He wanted to get married. When he'd talk about it, I'd feel so flipped out on the inside.
I pushed myself to just ignore the internal flip out, thinking it would help to just make myself take the huge leap. I told myself that it was the leap itself that was generating the fear and anxiety (because it IS truly a giant and scary leap to head toward marriage again!). I thought that once I just took that scary leap and agreed to get engaged, things would settle down and I'd adjust to this new and huge thing. I, like you, would look at all of the good things and tell myself I was just scared, and rightfully so because it's so huge. Id also cause myself to look at all of the wonderful things about him and our relationship.
I agreed to marry this man. It did not get better. It got worse. WAY worse. I was waking up in the middle of the night with terrible anxiety. I had no peace at all, awake or asleep. I tried to ignore it for months.
I actually ended up ending the relationship completely. It was very difficult to do.
But honestly, once the dust settled, to my surprise, I felt a such peace I dont know if the problem was me (I wasn't ready yet), or him (that he wasn't right for me) or what. It's like my mind saw all the good stuff and thought 'what more could I ask for???..he's got all the check marks! ( well MOST, and nooses gonna be perfect ' But my heart, or my gut' maybe ? was so terribly uneasy.
It's been a month since we broke up and I still feel such tremendous relief. And another weird thing is that I have had absolutely no regret. I keep waiting for the regret....he was a great guy in so many ways. There was ALOT of good.
It's very weird and I don't understand it at all. I just know that I did the right thing by the peace vs complete anxiety. I've decided through this ordeal that that is going to be my new life strategy... 'Follow my peace'
Good luck. This stuff is so difficult to navigate.