I, 18 F, have been dating my boyfriend, 18 M, for 3 years, who I'll call Tim. I sleep over at his place atleast once a week, usually once on the weekend and once during the week as we attend the same school. I've been best friends with a girl named Sophie, 18F, since I was 6. In the past few year's she's become incredibly dependent and clingy. She constantly asks in front of my boyfriend if I'm still her no1, and says really odd things like "I'll be sad when you have a kid because I won't be your priority anymore." This clinginess has extended into my relationship, with her asking to stay the night at my boyfriend's on formal (prom), and just the other day asking to spend the night at my boyfriend's on a week night as I was staying and she was going home. Sophie has been hanging out with my boyfriend and I a lot lately, and it makes me suspicious of her intentions. Almost 60% of the time I hangout with my boyfriend, Sophie comes aswell, and I know I should be able to say no but Sophie has Bipolar disorder, and as her "favourite person" I'm petrified of harming her mental health. I've noticed weird behaviour between the two of them lately, but I can't tell if I'm paranoid. Today she was touching his back and asking me if we could hangout with him. On days that I don't come to school, Sophie also asks to hangout with him alone when our friends are at school. It crosses my boundries, but I've talked with my boyfriend about it and he doesn't seem to think anything of it, infact, he isn't oppossed to her staying the night at all, which just further makes me feel like an asshole when he says yes to her staying and I say no. So am I the asshole for not letting her stay the night at my boyfriend's house?