Surprise Me by Sophie Kinsella

Those we think we know best can sometimes surprise us the most . . .

After being together for ten years, Sylvie and Dan have a comfortable home, fulfilling jobs, beautiful twin girls, and communicate so seamlessly, they finish each other's sentences. They have a happy marriage and believe they know everything there is to know about each other. Until it's casually mentioned to them that they could be together for another sixty-eight years... and panic sets in.

They quickly decide to create little surprises for each other, to keep their relationship fresh and fun. But in their pursuit of Project Surprise Me - anything from unexpected gifts to restaurant dates to photo shoots - mishaps arise with disastrous and comical results.

Gradually, the surprises turn to shocking discoveries. And when a scandal from the past is uncovered, they begin to wonder if they ever really knew each other after all...