Standard Deviation by Katherine Heiny

 Graham is married to cool corporate lawyer Elspeth but cheating on her with the younger Audra. Elspeth finally leaves him and he marries Audra. Now it's 10 years later and he's wondering if he made a mistake. Perhaps he and Elspeth were really better suited. Because Audra is a chatterbox who sometimes makes things up and is possibly cheating on him. But he and Audra have a beloved son with Asperger's who needs stability in his life. What will Graham do?

This is an interesting character study that would make for a good book group discussion. Some parts are extremely funny and some parts are downright sad. But I did get pulled into the story and was dying to see where the author was going.