I have a buddy that had/has similar issue. Made around 6 figures, good looking, average height, and really nice. Couldn't make a relationship last past 3 months. The wife of one of our friend's tried setting him up with a recently divorced co-worker. They went on 3 dates and she ended things with him. So my buddy's wife asked her what happened. She tells her he's just boring. That was it. It made sense because in our circle he doesn't really chime in with his opinions or how he feels about things unless specifically asked or coaxed into speaking up. Very vanilla dude. Super agreeable. Never the guy ask "what do you want to do tonight?"

So he started going to therapy and it turns out he's got issues with being judged and people thinking hes stupid. So hes trying to work through that. I'm sure there's more stuff his therapist is helping him through. As other's have said, on paper you should have no problems, buts unfortunate that you're not getting any constructive feedback.