Hey Pandas, Aita For Not Talking To My Friend?

Posting this here since I can't due to rule 11 on r/aita.

It all started a few weeks ago. My friend, let's call her Alice, told me she was going to eat lunch with somebody that I know but I don't eat lunch with. (Alice used to eat lunch with me everyday.) Of course, I wasn't bothered. I have one class with Alice, and I'm very academically focused on lessons. But whenever Alice said hi, I would say hi back. So this goes on for a few weeks, and I notice her starting to act strange around me. Then, lo and behold, one week ago, she sent me a sticky note in class.

"are you mad at me?"

I'm not one for note-passing, and there was a lecture going on, so I was planning to tell her after class that no, I was not. She also knows I am like this, so it's not like I was ignoring her out of the blue. So I focus on the lecture, and another sticky note pops up.

"you're not being a very good friend."

Now I'm confused. It's not like I was trying as hard as possible not to talk to her. After all, she knows my personality as a "focused student" during class and she was the one who had told me in the first place she was going to eat lunch with someone else. I never get the chance to explain it to her after class because she leaved very quickly, and I never interacted with her again.

AITA?

TD;LR, Friend starts eating lunch with someone else, sends me a note few weeks later saying I'm a bad friend