I've commented a couple of times on this thread, but what I really want to say is going to turn into a wall o'text. Feel free to skip to the bottom for the tl;dr version.
When I was in my late teens, I decided I wasn't going to marry before I was at least 25. I was pretty sure I didn't want to have kids. At age 22, I had a rare form of cancer. It was a huge awakening. I learned what matters most is the kind of life you build with your family, the quality of friendships you create, and your connection to the wider community, not the fancy shit you can buy. My life goals changed radically. I wanted to marry and have four (!) kids. To that end, I dated my brains out. I even shifted careers because mine involved too much travel, which made dating difficult. I decided to sell Men's Clothing at Nordstrom in my major city. Except that the work was hard and the pay low (but good for retail), it worked like crazy. I met new and interesting people every day. I also joined a church and took up golf, among other things. I was determined to meet my mate so I could fulfil my dreams and what I believed was my destiny.
Years passed. I had a number of good-to-great relationships. I even had a ring, a date and a dress once. I yearned to start a family. Alas, I never got to the altar. Sometimes it was my choice to end the relationship, sometimes I got dumped. Okay, more than sometimes. Probably 50/50. I was actually pretty selective in who I dated, weeding out those who weren't serious or were obvious mis-matches, so many of my relationships seemed to have lots of potential.
Every one of the relationships that I ended was for a variation of the same reason: I always knew how I wanted to feel before I got married. Once I got to a point in dating someone when I knew I wasn't getting the "feel", I was done. Simple, complete, kaput, over. I trusted my gut completely, but I know I broke some damn good hearts along the way. I got the shit kicked out of mine plenty of times, too.
Every time I got dumped, I felt the same way you did, always wondering why, and what was wrong with me. What could I have said or done differently to make things work? It took me for-fucking ever to realize they probably wanted to feel a certain way too. For whatever reason, they just weren't feeling it. And that had to be a good enough answer for me. Until that realization, I wasted So.Much.Time. Days, weeks, months and in two cases, years looking backwards, wishing for what might have been, wondering what I could have done differently, longing for a shot at redemption*. I'm sorry to say it took me a hideous number of years to figure out what a futile mind-fuck that was.
My dreams of having children slipped away, my chances of ever getting married seemed non-existent. I just kept on living my best life. I got a better paying job, I traveled more, volunteered in my community, bought and sold a couple of houses, and worked toward FIRE. In general, I just tried to build and live the best life possible. It worked. I was happy and my friends, especially the married ones, often commented that they wanted to have my life.
Fast forward: a long-ago acquaintance and I crossed paths when I was 54. He was a recent widower. Yup, lightning struck and we got married. OMG, so many flying pigs and hell freezing over jokes from friends, family and colleagues!. We've been married for six years and the wait was worth every fucking minute. Finally, finally, I do not regret a single relationship that happened along the way, because I learned from each one, and where I ended up was so amazing. Worth all the angst.
Tl;dr: The right person is out there for you. They just might be busy right now. Let this one go. In the end, you will not regret it.
*That's not a Hamilton reference, it's the great, great Paul Simon, on the amazing "Graceland".
P.S. I quite agree with lexde's cross post.