When James threatens Bella, Carlisle makes the declaration that "She's with us." At the end of the novel, Bella says she'd side with the vampires if they attack the prom attendees - as well as affirms her desire to become a vampire. In this sense, she is like a bride waiting to be accepted by her new family - another rite of passage that many adults face. Whether or not she will be welcomed in this manner is not determined by novel's end.