I honestly don't know. I never had a boyfriend at school or uni. I've been single most of my adult life - now 50s. The relationships I have had were mostly long distance.
I don't think I'm hideously ugly, though not the most beautiful woman in the world either. I'm fairly intelligent and can manage a conversation on many subjects. I love sex and apparently am good at it. I earn my own money, no debts.
I have been on OLD the last couple of years, and yes, there are some awful men, but there are some gems in between. I had a wonderful relationship last year with the most amazing man I'd still give my right arm for. And I've recently started seeing another guy, who is not as amazing, but still pretty good. But why it didn't happen in my 20s, 30s, 40s... OLD means I am not invisible in the way I have always seemed to be IRL. And having been single most of my life, I got on with life and did things I wanted to do (as far as money allowed,) and so anyone else in my life needs to enhance it, and fit in with what I already do.
But I have often wondered why no one wanted me. An old friend, whom I've known since childhood, said a few months ago, "I never understood why you never married," as if I had spent all my time turning down the offers. But no one ever asked, and mostly they didn't ask for a first date, let alone anything more, and the few I asked out said no.
It doesn't matter, but it has puzzled me at times (and I would have liked a lot more sex.)