Eclipse explores sex as both a physical and emotional union of two people. Sex as a purely physical act tends to be violent and dangerous in this book. In Rosalie's case, her fiancé assaulted her sexually because he had no feelings for her. For Bella and Edward, sex represents the consummation of their love for each other. It's an act of body, mind, and spirit, involving great trust and vulnerability. For Bella, it's also a deeply human experience, which is why she wants Edward to make love to her before he turns her into a vampire.