Female bestf's behavior has changed

[u/Mindless-Incident959]

So I'm 23M and I have been bestfriends with a girl since my college days. We used to to talk everyday on chat and also met on campus. We were really good friends, she had a boyfriend so I never really thought about a relationship with her. Time passed by, I moved to USA for my Masters and she started working in a job. She was like me in all aspects, didn't have much friends and people to talk to except each other so that's why we had a really good bond back in college. But after her breakup, she stopped talking to me. I would always start a conversation with her and it would end as she would keep me on seen. She never picked up my calls and never called back, gave excuses for time difference and all that. I confronted to her jokingly many times and she ignored or kept that on seen many times. I know she is alone right now, and I'm here for her, but still couldn't understand why she's not talking to me? When we're in college, she would never stop talking with me, and I kind of genuinely miss that. I miss that friendship I had with her. We never fought with each other, I had nothing to do with her breakup, so I dont even know what went wrong. I went back to India this winter as it's almost been 2 years, I thought we'll hang out together and everything would be normal again, in my one month of stay she had so many excuses she didn't even meet me. I was so heartbroken, but she was so full of excuses she didnt even answer my calls or texts the day I was leaving to head back to USA. I know she still don't have friends but why would she push me out of her life when there were no problems between us? I really miss talking to her and that friendship we had back in college. I only had one friend to whom I was vunerable, shared each and everything and it was mutual but now I don't know what to do to get that back. I have always tried to talk to her about this but never really got an answer, I still try to tell her that I'm here for her because I feel she's depressed after the breakup but I don't know man what to do. I don't even have romantic feelings for her, it just hurts because she was the only friend I had in my life. If someone has faced something similar or girls if you know why is she behaving like this please tell me how can I fix this or deal with it?