Send me feedback: Did I get too attached to a person for my own good?

I have BPD, autism, cPTSD, and probably other things that are too esoteric to get into, so please bear with me while I get into this.

Back in about 2022, I started talking with a person I very much enjoyed the company of. We're both left-leaning (they're a bit of a radlib, I'm a communist, but in our area they might as well be Fred Hampton) and we talked daily for over two years.

Then some workplace drama happened and they - along with 2 other co-workers - were determined to leave over it. I stayed because I can't take sudden changes, and I expressed that to them, which they seemed sympathetic to. We continued talking daily for the weeks between the blow-up and their eventual departure, and I expected us to stay on friendly terms, but that didn't happen.

Basically, I kept reaching out and they just moved on. They never reach out to me despite how much we talked about similar interests and hung out outside of work once and how much they told me about their family life, so I'm confused. I thought this person was probably my closest friend in my area, but I seem to be nothing to them. Is this just me misreading a work "friendship", or did I get just dropped the second I was no longer useful to them? It feels to me like the latter because of how they had nobody to talk to after our mutual coworkers left and I was the only person they had left to talk to daily, but maybe I'm being unfair about that. Still, talking to me daily and then not even wishing me a happy birthday or a happy holiday after I always did that for them makes me feel insane.

Anyway, I'm sorry for the ramble. Just please give me feedback.