We all live in a uni flat and get along very well, problem is my uni flatmate who is a very good friend is being lead on by one of our flatmates, on two separate occasions she has invited 2 of her friends to the flat and he got with both of them and actually started liking one of them but she had to move back to where she lives.
Problem is whilst drunk he told her he liked her back and now they're constantly getting with each other then next day he will tell me how he doesn't like her he just finds her attractive and he's only doing it to get closer to her friend that moved back to where she lives which is around 500 miles away.
I feel like if I tell her it'll ruin all of our friendships and obviously it will upset her, but the thing is she 100% knows what's going on but can't help herself for whatever reason as she has told me he is constantly mentioning her friend and even told her he likes her - surely when you hear that you would be gone yes?
She has now started doing stuff to try and make him jealous such as facetiming guys that like her, kissing random guys whilst he is in the club with us, and he says he doesn't care and just wants to get her friend but then after the nightout he would go in her room and have sex etc, she just obviously has no self respect.
I'm kindof lost and unsure what to do next, any advice would be great... Thank you!