Her Fearful Symmetry, by Audrey Niffenegger.
The problem was located in the word how: he would live, but without Elspeth the flavour, the manner, the method of living were lost to him. He would have to relearn solitude.
This is the second novel by the author of The Time Traveler's Wife, which was recently made into a movie (sidenote: both the novel and movie were great), and thus I shouldn't have been surprised by its weirdness. The novel had many twists and turns, especially at the end, and it was a modern-day ghost story of sorts. It's definitely worth reading, but like I said, is very strange at parts (much like The Time Traveler's Wife, I suppose).
3.5 out of 5 stars.