Ending (spoilers obviously)

Interesting. I didn't think of it that way. She seemed to want to be with him. I just assumed it was some metaphorical thing about how you die with the guilt of knowing you killed someone.

Oh wow. I didn't notice it the first time I watched it, but you're right. I do believe she killed him at the end. Everything about the scene screams it, and we know she has that gun. Problem is, as abusive as her boyfriend was, she loved him... which often happens with abused women. And the thing she said about digging two graves...