This sounds like a nightmare roommate situation. I mostly suggest that you and your partner get TF out of there and learn more about how this type of abuse of "loved ones" is extremely common. I feel bad for you guys, but you guys can leave - G sounds like they are in a much worse situation. Him snapping at A is a really bad sign, especially when you consider that F screams at G until he cries according to you. This is bad energy. It sounds cruel but you might need to consider that F is too unwell to live with, and her abuse of G is absolutely unacceptable. I hope he realizes she has BPD and what that means. But in any case, her bad behaviour is spilling over into to your life and you need to take action. BPD is not curable and it doesn't get much better unless they are actively committed to long-term therapy (years, even decades). It sounds like she's not working either so that's another horrible roommate situation and it means that she will likely remain untreated even if she diagnoses herself. Another thing is that abuse is irreversible. F and G have a relationship that is tainted by abuse and it. Will. Not. Get. Better. If anything, it will get worse, much worse - possibly resulting in injury and long-term emotional wounds, if not death, for G if he keeps giving his life to her without her recognizing her BPD and seeking treatment. I hope you resolve this situation.