Many of our favorite old fairy tales have this ending: "So they were married and lived happily ever after." And this is what many of us would like to think about marriage . . . happily ever after. However, we all know from divorce statistics and the brokenhearted letters to advice columns that many couples do not achieve marital happiness. There may be more divorces today, but that doesn't necessarily mean that there is more unhappiness in marriage. We have no idea how many couples one or two generations ago stayed together because it was impossible for them to separate. People who are ready...