[Serious] How Are People Actually in Relationships?

So I want to be clear that I'm not asking this for sympathy or to soapbox. I am asking out of genuine confusion and curiosity. Being in a relationship seems very common. Everyone I know has either been in a relationship or is in a relationship, but the concept of getting into one just seems so foreign to me, despite my openness to being in one.

Here's some context: I live in NYC, and I have all the traditional qualities that the internet thinks girls want. I'm a former D1 athlete and still look the part, have a fantastic job that I'm passionate about, and a wide variety of interests outside of it. When I was on the apps, the results showed, and all I had to do was go through my likes to find a date. Pretty consistently, we'd go on 1-3 dates, they would seem VERY into it, and then I would get the message "You're an amazing guy, but I don't feel a connection." At first, I attributed it to certain things I said or did, or didn't do (being awkward at times, talked too much/little about myself, lack of flirtation/too much intellectual talk, etc). Sometimes there genuinely wasn't a connection and it was painfully obvious, but for the others, no big deal, I'd just learn from my mistakes.

Over time, I got "better" at this, and even started cold approaching girls (politely). About 1/5 girls I'd ask would lead to a date. They were always so excited to be on the dates, as was I, and their excitement made me feel really confident in myself. They'd even tell me how they told all their friends about our "meet cute."

Yet without fail, regardless of the level of physicality too, I've continued to get the same message. At this point, I just genuinely don't understand how people find themselves in relationships. It seems like something so basic, but do people only want to go on 1-3 dates? I am very open to the idea that I'm the common denominator in all of this, and that there's something that I'm doing wrong, I just never get any negative feedback outside of these messages, so I don't really know what to make of the situation.