I don't see why they couldn't just -I donno- unfriend you then quietly go on their way.

I know! That's what annoyed me the most. People come and go, it's the law of the internet, but bringing it to my attention just to make me feel bad gratuitously is a real dick move.
Thank you very much for your very kind comment, it did make me feel better :) Don't freak, I'm gonna virtually hug you now. *hugs*