Ok I figured it out

Im honestly kinda confused about that aswell, but im 90% sure that the roommate was a past victim of rape and McQueen persuaded him to do the film still knowing that, or the roommate was in pain and McQueen didnt notice and it felt like rape or smth.

Those are the theories I came up with, but they could also mot be true but it feels like thats what it was implying lol, hope this helps.