Gone Girl, the thriller by Gillian Flynn.
The narrative goes back and forth between a husband and a wife, giving the reader both perspectives on the troubled marriage, and the much more troubled psyches of the spouses. The wife, Amy, disappears at the beginning of the novel, and the husband, Nick, is the main suspect.
The segments of Amy's diary really grated on me, and I had trouble getting into the book because of that, but eventually I felt invested in the story, which picked up momentum, and paints an eerie portrait of a disturbed mind.
Gone Girl isn't great, but it was an enjoyable read. And I'm looking forward to seeing the movie when it's released...