Sorry, I don't know how old under-grad is, like 18/19?
Anyway, as I get older I tend to think that people can 'like it or lump it' and I don't want to waste my time on people playing games or the school-yard politics... didn't mean to sound so harsh there, but that's what I'm telling you; just ask her. Next time you see her, just say something like 'look, I'm not trying to be pushy, but have I done something wrong here? Because you say you want to be my friend, but you never reply to my messages or call me back or whatever, what's up?'
But I'm bitter and twisted with no friends, so you probably don't want to listen to me