Why is this girl ignoring me?

So i would say that me and this one girl in my cl are pretty good friends. Back in October when we first met she would always talk to me and things like that. However, very recently she has been somewhat ignoring me. She doesn't really approach me anymore (although she does once in a while). but if i approach her and talk to her then she is very attentive, so i dont think shes mad at me or anything. we also sit at the same table in cl and i sit across from her and she never looks me in the eye or in my direction. why is she acting like this?