Griffin is a happy man. Settled comfortably in a Chicago suburb, he adores his eight-year-old daughter, Zoe, and his wife, Ellen - shy, bookish Ellen, who is as dependable as she is dependent on him for his stability and his talent for gently controlling the world they inhabit. But when he wakes one morning to hear of his wife's love affair with another man and her request for a divorce, Griffin's view of life is irrevocably altered. Overnight he goes from being Ellen's husband to being her roommate, from a lover to a man denied passion and companionship. Now he must either move on or fight for his marriage, forgive his wife or condemn her for her betrayal, deny or face up to his part in the sudden undoing of his seemingly perfect life.

From the New York Times bestselling author of Open House and True to Form comes a brilliant novel that charts the days and nights of a family whose normalcy has been shattered. With startling clarity and a trademark blend of humor and poignancy, Say When follows a man on an emotional journey to redefine his notions about love and happiness and asks questions relevant to any contemporary couple: when is a relationship worth saving and when is it better to let it go? Might a man and a woman define betrayal differently? How honest are we with those to whom we are ostensibly closest?