I agree with McTeague that for Pat and Tiffany, it is not so much a happy ending but more a little moment of victory. Russell in no way implies that their problems are solved. However, I do believe that with his film, the audience wants a happy ending. We are hopeful creatures after all. I don't think Russell betrays his characters for one moment. Just that people are going to read whatever they want from this ending, which I thought was bittersweet and perfect.