Sometime ago I came across a story a while that was followed by a (i think) three part series. In the initial story a guy moves in with a friend and his girlfriend, she starts teasing him, it turns out that her boyfriend wants to share her. In the followup series all 3 of them end up visiting the girlfriends family and the whole thing turns into a weekend of everyone (including her father and brothers) banging the girlfriend (and her sister if memory serves). The sex was definitely on the raunchy/rough side throughout all the stories. Any chance this sounds familiar to anyone?