These are questions you should ask to a very good life friend or a professional.

If I had to guess, I'd guess that it's a lot to do with your father withholding affection from you as a little kid (i.e. under-10), and inadvertently teaching you this pattern. It doesnt sound like selfishness, (I think you'd respond positively to someone saying they like you, if it was)

But, life will change. It's the only thing you can really guarantee, that life always changes.

Because at some point, you figure out the affect of what is causing this. Congratulations; I am 51, and finally figured out I'm very lonely. Keep up the great work, and don't be so hard on yourself for wanting to have someone to talk to.

I wouldn't be surprised however, if you talk to the same guy on a regular basis and he develops feelings for you.