You've rejected girls that you didn't even take the time to get to know. I know of some very strong, happy relationships where one party or the other started out thinking that the other party wasn't that attractive or interesting and then, after some time with the other party, fell head-over-heels in love.

The reason you have a hard time knowing what to say to girls is that you don't take much of an interest in finding out what's below the surface. You kind of are dooming yourself.