Hi everyone, hope you can help me remember this tough one.
In the beginning one of the characters came back home and found his girlfriend fucking a friend of his. The two guys got mad at each other, both claiming the girl as their girlfriend. Later she admits she cheated, and it ended in a threesome. The very last scene saw the two of them walking outside the apartment, and the girl telling them to do it again from the window.

As you can read, I remember clearly the plot, but I've done many searches and yet I didn't found it.
Hope you can help me.
Thanks in advance.

P.S.
Sorry for my bad grammar, English is a second language.