Has anyone else been through this? What's your experience?

I’ll be 21 next month and I’ve never been in a relationship, never been asked out, kissed or anything. Every time I’ve liked a guy he’s either been unavailable, uninterested, or most recently, gay.

As stupid as this probably sounds, I feel cursed because everyone else around me, all throughout my life, seems to be able to get into relationships left and right with no problems whatsoever. But with me there’s always something blocking it. And it hurts even more b/c I’ve actually met a guy in college that’s literally everything I’ve ever wanted… but of course he’s already in a serious relationship. So right person, wrong time.
I’ve gone to guys w/ my feelings, and they acted cool about it for what, a couple days? Then they basically just started ignoring me and treating me like I don’t exist so it makes me never want to approach/make the first move again. So it’s not like I haven’t done that, before you say “why don’t you make the first move”.
I really try not to let it get me down; I’m just focusing on improving myself and school and everything, but it still sucks because I wonder if it’s going to be this way forever. I know I’m still young but I’m not getting younger either.