Judging from what you said above, it seems that your circle in the class is still relatively narrow at present, which can also be related to your sensitive personality ~ So, you are very concerned about the girl's reaction and warm relationship in front of you (you have always been her close friend).
Actually, you just started the second grade. Say something you don't like very much, and you can't accurately judge what a true bosom friend is. Therefore, what you have to do is to expand your circle of friends (called intimate circle in psychology) while studying hard, and be a girl who can talk with different classmates and have several friends who often chat and study. As for that girl, judging from the materials you provided, I can't say that she doesn't care about you, or arbitrarily think that she doesn't treat you as a friend ~ but one thing, she certainly doesn't want to care about you all the time as you think, and her own circle of friends is bigger, huh? It seems that your academic performance is better than her, which may be the reason why she is a little distant from you. Personal experience for your reference.
So, first of all, you should pay attention to your study. Secondly, don't be hard on her when making friends. People can always think that you can find a few intimate friends (grades and personality) ~ Come on! ! !