Are my friends being mean?

warning: advice may not be useful! But it’s my opinion

Honestly, if the person you don’t like is hanging around with your flatmate, you can’t do anything about it because it’s their choice. If you want to be part of the experience with your flatmates, e.g going to the library, then involve yourself in it. Although it may seem tedious, you’ve got to put yourself out their imo.
Obviously, it’s a pain in the ass but you’re literally living with them, so try to deal with them. Also, it’s no crime for your flatmate to try make new friends, although I don’t know them personally, just because a person is spending time with others doesn’t mean they don’t still think of you as a friend.

Hey, thanks

my flatmate who made friends- I have no issue with, it’s that she stopped speaking to us for three months and sorta started sleeping over at friends and we were worried about if she was okay haha but is suddenly back on the scene lol…previously my other flatmates were *****ing about how she dropped us for no reason (known to us)

and yeah it’s not that I don’t like anyone it’s just my flatmates behaviour is kinda tumultuous (dramatic word but I can’t think of another one atm), but I just find them quite cliquey sometimes considering I might live with them next year

but thanks I get the getting involved bit and I get too much into my head at times