Oooof. Had a similar situation. Classmate from my undergrad cohort just started texting me a few months ago about after a year I had already graduated from undergrad. Kept bothering me every day about her first job and all these little things about her mom, and she would just go and on. Being a nice person, I didn't mind until I started my first semester of grad school. And didn't have time to constantly communicate with people.
Anyways, she basically looked at me like a big brother cause im a few years older than her. It got to the same point as you OP. She would keep on texting me even if I didn't reply, ask for help about the simplest things, or talk her day as if I was in a relationship with her. I had got to the point. I wanted to block her and ghost. Furthermore, I have never met in person since at the time of college everything was remote, so I don't know why she wanted to be friends with me. My guess was that everyone she talks to just turns her away.
So, i got rid of her by pulling a Ted Mosby (tactic from HIMYM). I told her I really liked her and that I wanted to go out with her, but she was reluctant about it and just wanted to be friends. So i said, "I can't put myself through that because I think I love you even when we don't talk" and she just slowly stopped texting me after that because I wouldn't reply to her "can we still be friends?".
I know this isn't the answer you were looking for. But these other reasons I came up with but didn't use to stop communicating with her.
I am just starting a relationship with someone, and I can't divide my attention between both of you.
I don't see this friendship working out. It seems one-sided to me, and I can't stop thinking you're using me.
So listen, is there any way you can reach out to me about matters related to only academia(work) as I swamped with personal matters.
Reply with Busy Right Now. Will talk later, followed by still busy.
Anyways I hope it works, and if all else fails, you can transfer schools j/k