I dnt know if I’m being unreasonable that’s why am asking for help.

My bf and I are in a long distance relationship. There’s this girl that I asked him to stop talking to because it makes me uncomfortable and he told me that he likes to be friends with her which was a red flag for me. He also told me that its hard to ignore her since they live together in the same apartment (its a big apartment with a lot of people)

We’ve talked about it many times and frankly I’m tired of bringing it up but recently I caught him still talking to her and bonding. I havent confronted him yet. I dnt know if I should. Am I being unreasonable? What should I do?