I hate to make sweeping generalizations, but here come a few. Guys are dumb; I know, I am one. We tend not to think about how we feel, let alone have any clue how you feel. Guys also basically make one of two assumptions until they're slapped with the reality that it isn't so; on one hand you have the guys who think every woman they encounter is into them, and on the other you have guys who think no one wants them and they're going to die alone and probably deserve to for some reason or other.

So you start acting into a guy and two things happen: first, he doesn't notice because, like I said, guys are dumb; then he freezes up because he's either not sure he's reading the signs right and doesn't want to make a move and get rejected or look like a jerk, or because he really isn't into but thinks it's cute that you're into him. So you give up, and, if he's one of the guys who thinks he'll never be liked, he realizes that he may be wrong and he also may have just blown his only chance; if he's one of the guys who thinks every woman he's ever met wants him, he wonders why all of a sudden you don't seem to, in which case he'll chase until you start acting into him again and then he'll go back to ignoring you because you wanting him was really all he wanted.

There are two ways to deal with this. First, you could play on our dumbness by flirting and whatnot until he asks you out all the while thinking it's his idea. Secondly, you could circumvent it by being completely up front about how you feel, because it's the 21st century and it's okay for a girl to ask a guy out.