Surprise Me by Sophie Kinsella

When you feel you have the perfect marriage, perfect jobs, wonderful children, what more could you want. When Sylvie and Dan find out that they could be together for another 68 years they start to question things. They want to bring spontaneity into the relationship and make sure they enjoy everything and don't get bored with each other. This leads to some sketchy situations and some huge misunderstandings. A very fun read full of angst and laughter. Don't worry about the future, enjoy what you have now.