 Serena fears that she has lost Haley 's love forever , now he knows she has deceived him . Haley , however , had known about the program for months , and instead of ending the affair , had decided to turn the story into a novel . The reader now discovers that the author of Sweet Tooth is in fact Haley , despite its being written from Serena 's first @-@ person perspective . As the novel ends , Haley asks Serena in a letter to marry him . 
