The Time Traveller's Wife -- Audrey Niffenegger

The first time Clare met Henry DeTamble, she was six and he was forty-two. The first time Henry met Clare, she was eighteen and he was twenty-six. But this is to be expected when one is a time-traveller; and that is precisely what Henry is. He finds himself uncontrollably and unexpectedly hurled back and forth through time, visiting people, places, and events from his past and future - and never able to change what will happen, or rather, what already has. And Clare... Well, Clare waits. Always for Henry. And as she waits, she proves that love can overcome everything - even time.