I'm trying to find a movie where a male actor seduced his brother's girlfriend.

I'm trying to find a movie where a male character seduced his brother's girlfriend. I was thinking it had Aubrey Plaza in it but now I'm not sure, because I've looked through her movies and nothing is ringing a bell. I think I saw it around the same time as Safety Not Guaranteed. All I remember is that the girl's boyfriend was kind of an average guy, not passionate, and his brother had a conversation with her about how he didn't "take her" aggressively, and she deserved better. And he told her to meet him upstairs (in his room ) in the house they were all staying in together, and had sex with her.