How does the author use foreshadowing in The Time Traveler's Wife?

The Time Traveler's Wife is divided into three books, each focusing on significant periods within Henry and Clare's lives together. The way the books are written is unusual, with diary entries that pertain to the past, present and future Henry. Niffenegger uses both flashback and foreshadowing through the book quite extensively. Henry goes back and forth in time, making it Henry's experience. Told from his perspective, it still enables us to develop a complete and indepth understanding of both Henry and Clare's feelings and perceptions.