(I'm still in highschool)
I transferred as a sophomore to a new hs in a completely new city, and it took a while to make my first friend. She was really friendly and funny, and thought of me the same way too. For the next year, I would offer her lunch I made and improve my productivity with school and the gym while being reassured that I could promise something for her.
That way, we were really close friends with a brother-sister dynamic. This year, as juniors, we still shared classes but we started hanging out with more different friend groups. We still texted to each other every night and talk for hours like nothing's changed from last school term.
However, she complained about another good friend of mine and I told her something that I didn't clearly think through... "please find someone else to talk to about this" and she stopped talking to me entirely (both text and in person) since late September.
I tried to say or send something I remember she liked to get a reply... but I didn't want to overdo it or be considered a stalker. My grades began slipping (in the most important year of hs) and I am barely able to focus whenever I'm in the same class as her. I get so lost in the classroom noise because I'm not a part of that noise anymore.
I've decided to just give her some time and space, and although I don't ever want to end a friendship no matter how bad a situation is (this might be a sign of attachment), I'm lost and need some extra steps for myself.
I still struggle to do what I want to do and whenever I go and have fun with my other friends, I think of her and feel guilty to the point where I can't enjoy myself.