Dating my friends brother
So she stopped hanging out, and me and her sister have grown to have a pretty strong friendship.It's been a while, but at this point the girl I dated is pissed I have a relationship atall with her sister.
As for the reverse, I'd find it weird for much the same reasons. However, in the movie she had HUGE reservations about her friend dating her brother, and so I thought it was kind of shitty for her to pursue it and kind of broke the trust between friends, I guess?
I say this as someone who has totally crushed on a friend's brother before, that I know I would find it weird as hell if any of my friends dated my brother.