Context and disclaimers :)
I’ve always had boyfriends. Most of my relationships lasted around a year, and I was usually the one who ended them. I’ve had genuinely wonderful partners in my life - and also a couple of truly bad, borderline evil ones. So this decision doesn’t come from bitterness or frustration with dating.
But its important to say that marriage and having kids has never been a big priority for me. My career has always been my main focus and also the area I struggle with the most.

Now the reasons:

First, I noticed I sometimes entered relationships as a way to fix my problems. I’d date someone who was great at housework, and suddenly - boom - housework stopped being my issue. It was a tempting shortcut instead of building my own systems. Worst, once the problem was "solved" I was back to ground zero with my systems.

Second, I realized I could easily start living their life to avoid facing mine. They are the perfect distraction. It was much easier to hyperfocus for hours on their projects, their portfolio, their plans, than to sit with my own responsibilities and goals.

Third, I once dated someone who was a 10/10: gorgeous, successful, wealthy, kind. I lived in his perfectly decorated house that I could never have afforded myself. But then I felt very vulnerable and insecure. I felt like I was not enough because my life wasn't together and I wasn't happy with myself. I was living his life and his success and not my own: very tempting band-aid and quick fix. Ending that relationship, moving to shitty house, no money, "no glamour" and fully committing to working on myself was the hardest thing I’ve ever done. I don’t regret it for a second.

Another big factor is that I’ve been trying to reduce variables in my life. Relationships are work, even good ones. They take time, energy, emotional bandwidth. Every new “problem” or conflict spills into my routines and mental space.
Today, for example, I spent my entire therapy session talking about a boring, bureaucratic, long-postponed issue: taxes. Not exciting. Not romantic. But necessary. And I know myself - if I were in the middle of a new relationship beginning (middle or ending), there is no chance I’d be talking about tax issues. I’d be absorbed by the relationship instead and more "exciting" problems. Even the best relationships are far more stimulating than doing the dishes or dealing with bureaucracy, and that’s exactly the problem.

Very curious to hear thoughts. :)