Why would a girl stare blankly at a guy?

Anonymous
I've caught this girl staring at me at college several times. It was weird, 'cause she looked at me blankly (wide-open eyes and no expression on her face at all).
Anyway, I did approach her, and she's nice, only that when we're alone we get alone great (laugh, smile, talk) but when we're in a group she just ignores me!
Why is she doing this?
I also remember I once looked up and she was with her friends, blankly looking at me completely absent from their talk.
PS. We're both 21.
Why would a girl stare blankly at a guy?
3 Opinion