Ch. 1 Boyfriend takes sexy pictures of his girlfriend. He tells her that he won't show anybody the pictures, but then shows two of his friends. They all come over and bang her.
Ch. 2 The boyfriend hasn't had sex with her since then, and the girlfriend's getting horny. She comes across the two guys from the last chapter, and bangs them. One of them puts it in her butt and she likes it. Later she asks her boyfriend if he'd like to try a different hole than usual. He assumes she's talking about her nose.
Lesson: Don't ever let your boyfriend take sexy pictures of you because they will always show their friends.