I Become Her by Joe Hart

It's only been ten days into their honeymoon cruise and Imogen suspects Lev of infidelity. And somehow during the argument that follows Lev goes overboard. It's a miracle he's found alive... an even bigger miracle he doesn't remember what happened that night. After they return home however, she's paranoid that he remembers more than he lets on and she realizes she never knew her husband at all.

Wow! This is even better than Or Else and I loved that book. There are so many twists in this book, told from different perspectives and timelines, and I never completely knew what was going on until the shocking end.