It isn't said, but it's really implied when you talk to Noelle in town :0

Like when you tell her that Susie's nice, she is relieved and blushes when she says that she should try talking to her (and that she might 'die' if Susie is actually nice). And if you tell her that Susie eats chalk, Noelle will ask what her favorite chalk color is, before realizing that a lunchbox full of chalk isn't the best gift to give!

So she either has a crush or just really wants to befriend Susie c: