Forever....

Katherine, in the middle of her senior year in high school, finds herself strongly attracted to Michael, a boy she meets at a New Year's party. As their relationship unfolds, the issue of sex comes up more as an emotional and health issue than as a moral one. Both of them are aware that physical intimacy is both common and complicated.

Their relationship progresses slowly as they begin to go on dates and trips together; they are accompanied on various meetings by Katherine's friend, Erica, who has known Katherine since the 9th grade and believes that sex is a physical act and not very romantic, and believes Katherine should "just get it out of the way." Erica and Katherine are also joined by Michael's friend Artie, who got together with Erica; they split up after he told her he was going to kill himself, but he didn't harm himself. He is a depressed teenager who doesn't know what to do with his life. He shows his depression when he attempts to hang himself from his shower curtain rod but fails and gets himself hospitalized for the rest of the novel.

Katherine and Michael go on a skiing trip, where they plan to have sex, but Katherine has her period, and they are disappointed. Michael teaches Katherine how to hold his penis(nicknamed "Ralph") and how to rub it correctly. When Katherine and Michael do have sex on Michael's sister's living room floor in her apartment, they are sure it seals a love that will be "forever". Michael buys Katherine a necklace for her birthday that says both of their names on it and it also says "Forever". However, separated for the summer by work that takes them to two different states, Katherine finds herself aware of the limitations of the relationship and is ultimately attracted to a tennis instructor, Theo, who is older than Michael. Theo calls her Kat, because everyone else is doing it, even though she is highly irritated with the nickname. She shares a kiss with him, and takes responsibility for breaking the news to Michael when he comes on a surprise visit. Michael realizes she has found someone else, and Katherine gives him back the forever necklace before he takes off. She realizes that she could get over it. The book ends with Katherine's mother giving her a message that Theo called for her.