Reasons why friend request on Facebook rejected by crush?

Is there any motive for a girl you suspect to have a crush on you for rejecting your friend request on Facebook when she's friends with most of my own friends on it despite the fact that she doesn't even talk to them in reality?
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+1 y
I can accept her rejection but it completely conflicts with the signs she shows in school. I catch her looking at me, her friends look at me, she smiles when I say hi, she laughs at any crap joke I make and she's nervous in my presence.
Reasons why friend request on Facebook rejected by crush?
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