How is Sofie's innocence destroyed in the book, Nothing: A Novel?

Innocence and virginity are a symbol of childhood, and Sofie being stripped of these things leads her down a darker path than any of the other students who give up things of their own. Hans is the one that suggests Sofie give up her innocence for the heap of meaning, and after he rapes her, she is much more cold and emotionless, demonstrating how such a traumatic event can impact anyone, but especially a child. As a result of having this forcibly taken away from her, she becomes mentally unwell and is sent to an institution.