Marriage is the process by which two people make their relationship public, official, and permanent. It is the joining of two people in a bond that putatively lasts until death, but in practice is increasingly cut short by divorce. Over the course of a relationship that can last as many as seven or eight decades, a lot happens. Personalities change, bodies age, and romantic love waxes and wanes. And no marriage is free of conflict. What enables a couple to endure is how they handle that conflict. So how do you manage the problems that inevitably arise? And how can you keep the spark alive?