Rose finally tells Simon about Maggie:
Rose: I was protecting (Maggie) because that's what I do. You need to know this, because if by some insane stroke of fate you do decide to marry me, she will make your life a living hell. You'll be begging me to kick her out, commit her, kill her, anything. And I'll want to, but I never will. (her voice breaks) Because without her, I don't make sense.