It is a love story about a man with a genetic disorder that causes him to time travel unpredictably, and about his wife, an artist, who has to cope with his frequent absences and dangerous experiences. Niffenegger, frustrated in love when she began the work, wrote the story as a metaphor for her failed relationships. The tale's central relationship came to her suddenly and subsequently supplied the novel's title. The novel, which has been classified as both science fiction and romance, examines issues of love, loss, and free will. In particular, it uses time travel to explore miscommunication and distance in relationships, while also investigating deeper existential questions.