What makes a good marriage? The mystery of why some marriages succeed while others fail is something couples have been trying to sort out for decades. Now, New York Times “”Well”” columnist Tara Parker-Pope has put marriage under the microscope, consulting with the world’s top experts on love, sex, and companionship to explore the vast scientific literature of human relationships. The result is simple, practical advice to help couples diagnose the health of their own marriage and lower their risk of divorce. (Author abstract modified)