Just how it’s seemed to me, but what I’ve seen happen a lot is this:
1) Boy sees girl and gets attracted/interested before girl.
2) Boy doesn’t communicate and so falls in love/lust/crush/whatever with his imagination of her.
3) Boy brings THAT when/if he gets around to approaching her, and THAT is weird for her since he’s nervous and thinking about something that isn’t her (and his approach is trying to cause something by himself, not create something with her), so she’s not attracted.
4) Girl is politely INDIRECT about saying no, but guy is listening for any possibility and hears it as NOT NO = MAYBE YES.
5) Boy goes into problem solving and causing modes, trying to change the polite/false MAYBE to YES. Girl experiences this as guy trying to get something he can’t get.
In this situation, the guy doesn’t know he can’t get it until she does something that breaks the illusion he has from his imagination and the MAYBE YES, politeness, lack of an answer, etc.