Well, let me start by reflecting a few things back at you that I've noticed you said.
- it sounds like you have no problem doing self work (therapy, meditation, working out, etc)
- it sounds like you have no problem trying new strategies around relationships
- it sounds like you have no problem getting first dates
So, it seems like the main problem is taking a potential partner, forming a serious relationship with them, and getting to the marriage point. The good news is you only need to do this successfully once. So it sounds like the deep question you need to solve is, why aren't any of these attempts working out?
I'd say the best advice I could offer for this is to follow up with people you've gone out with, and ask them why it didnt work out, and genuinely listen to what they say. You could say something like "Hey, I know it didnt work out between us, and that's okay. I'm seriously looking for a partner, and I've been struggling. Could you tell me more about what our interaction/relationship/date experience (pick the best term for the person here) looked like from your perspective? I think feedback you could give me would be help, and I'd be really appreciative"
For more misc advice I'd also say
- It sounds like youre spending a lot of time trying a lot of things and going on a lot of dates. Maybe try scaling things back so youre putting more effort into fewer things that have a higher potential. So it sounds like you have very clear relationship goals (marriage, kids, etc). I'd be very upfront about that (maybe mention it on apps, but at least on the first date 100% for sure). Cause like if they dont have the same goals, or are unsure, probably both people's time is getting wasted
- Check out the youtube channel healthgamergg. Its done by a guy who was a former yogi, and now is a physiatrist. The content is very therapy related, but he talks a lot about people who have a hard time with relationships. I think the quality of the stuff he makes is extremely high, and I've gotten a lot of value from it personally, so maybe you might as well.