Why would a girl distance herself from a guy?

Anonymous
lets put up this scenario:

A girl and and guy are good friends, but (I think) the girl realizes that the guy likes her a lot and she starts to distance herself from him, not totally, but enough for the guy to know.

is it because she is isn't interested at all and wants to distance herself to try and make him 'uninterested' in her?

or is it because she's likes him back but is shy and distances herself from him just because?

I'm sorry for such a question but I seem to be the guy in this scenario, and I really don't know how to react to her distancing from me. and, as obvious as it is, it's really confusing for me because I can't stop thinking about her.
Why would a girl distance herself from a guy?
5 Opinion