Well, she loses what basically gives her the drive to do anything in her whole life. She loses the man she's in love with, but she also loses her entire life plan, and she's so young to have to be forced into a decision like that. It's just a glorified, elaborate version of the worst breakup you've ever been through. All of a sudden you question everything. All of a sudden you know nothing and you're dropped in the middle of a freezing cold ocean. Oddly, we have a character that's warm enough and bright enough to bring her out of that, and it's truly gut-ripping. Because as perfect as Jacob is for her, she holds on to an ideal, the ultimate fiery love that she has for Edward even though it's not comfortable, it's not practical and it's not a good idea.