Honestly I get that he's gross and has personality clashes, but bottom line, you moved into his home, not the other way around and you have no right to go changing things or tell him he can't sleep on the couch, especially if that's something he did prior to your arrival. It would have been great if he'd been more sensitive and accommodating to you, but he was the one who let you move in to be with your bf, and now you think you can tell him what to do because his behavior bothers you in his home? Sorry sis but pack your bags, and keep em packed. If you want, ask your boyfriend to move in with you somewhere without his brother but you have no business demanding he change anything he's doing in his home. You owe him an apology.