How we cite our quotes:
Surely it was a good way to die, in the place of someone else, someone I loved. Noble, even. That ought to count for something. (Preface.3)
Bella sets the tone of the novel by explaining that she is about to die. She's willing to sacrifice herself in place of someone she loves (we later find out that it's her mother). Do you generally consider Bella a selfless individual?
[Edward to Bella:] "You put on a good show," he said slowly. "But I'd be willing to bet that you're suffering more than you let anyone see." (2.195)
This is one of Edward and Bella's first conversations. Again we see that Bella has a relatively self-sacrificing nature – she heads to Forks so that her mother can spend time with her new husband. Edward understands that Bella is making a sacrifice because he senses that she's suffering.
[Edward to Bella:] "Don't you see? That's what proves me right. I care the most, because if I can do it" – and he shook his head, seeming to struggle with the thought – "if leaving is the right thing to do, then I'll hurt myself to keep from hurting you, to keep you safe." (10.177)
According to Edward, he must feel a greater sense of love for her, because he is willing to sacrifice his personal happiness for her safety.