The Time Traveler's Wife
The Time Traveler's Wife by Audrey Niffenegger. Henry DeTamble is a librarian with "Chrono Displacement" disorder. At random times he suddenly disappears and finds himself in the past or future, usually at a time or place of importance in his life. From his point of view, he first met his wife Clare when he was 28 and she was 20. She had known him her whole life. The book alternates from Henry's point of view to Clare's. Publisher's Weekly described it as an "intriguing science fiction concept, a realistic character study, and a touching love story".
I thought it was fantastic! The characters had a lot of depth and the story was believable, even with the time travel. It was funny, touching, and even tragic. I recommend it!