This girl has a boyfriend but looks at me a lot at school?

when i'm at school when we are having cl she looks at me her eyes start to look to the side almost like she is not looking she only looks when i'm not looking at her part of the clroom at recess or lunch time she goes to where i eat she only pes by and goes back out the way she came she didn't even talk to someone and one of my friends said she has a crush on me but that was a month ago and she also after dismissal tries to sit next to me in the waiting area and she says that she has a crush on her boyfriend she does not know that my friend told me oh! and my friend used to be her friend also last month when i ask her who is your crush she just says it's her boyfriend but now she says it's nobody.