Behind Her Eyes by Sarah Pinborough

Louise is a single mom, a secretary, stuck in a modern-day rut. On a rare night out, she meets a man in a bar and sparks fly. When Louise arrives at work on Monday, she meets her new boss, David. The very married man from the bar… who says the kiss was a terrible mistake but who still can’t keep his eyes off Louise.

And then Louise bumps into Adele, who’s new to town and in need of a friend, but she also just happens to be married to David. As Louise is drawn into David and Adele’s orbit, she uncovers more puzzling questions than answers. The only thing that is crystal clear is that something in this marriage is very, very wrong, but Louise can’t guess how wrong―and how far a person might go to protect their marriage’s secrets.