... I would agree that it's the weakest part of the film. The moment where I said she addresses the 19-year-old as a human, she isn't even addressing her-- she's addressing Charlie. "Be good to her." It's a nice, tender moment, but yeah, the girlfriend's part is broad, even in that scene. (Although I do like that she conveys one of the central themes of the film-- "anger begets greater anger"-- because she read it on a bookmark in a book she can't remember. Feels appropriate considering how prevalent and messy all the anger is in the film. And, as Walleye said below, her outsider status definitely brings something to the table as well.)

I still love the movie. But I don't begrudge anyone who doesn't like that character, really.