New York Times columnist David Brooks argues that there are three different lenses through which to think about marriage decisions—the psychological, the romantic, and the moral lens.

Most of the popular advice books adopt a psychological lens. These books start with the premise that getting married is a daunting prospect. So psychologists urge us to pay attention to traits like "agreeableness," social harmony, empathy, and niceness.

The second lens is the romantic lens. This is the dominant lens in movie and song. More than people in many other countries, Americans want to marry the person they are passionately in love with. But in their book "The Good Marriage," Judith Wallerstein and Sandra Blakeslee concluded that 15 percent of couples maintain these kinds of lifelong romantic marriages.

The third lens is the moral lens. In this lens a marriage exists to serve some higher purpose. Brooks points to Tim Keller's book "The Meaning of Marriage," where Keller argues that marriage introduces you to yourself; you realize you're not as noble and easy to live with as you thought when alone. Brooks writes:

In a good marriage you identify your own selfishness and see it as the fundamental problem. You treat it more seriously than your spouse's selfishness. The everyday tasks of marriage are opportunities to cultivate a more selfless love. Everyday there's a chance to inspire and encourage your partner to become his or her best self. In this lens, marriage isn't about two individuals trying to satisfy their own needs; it's a partnership of mutual self-giving for the purpose of moral growth and to make their corner of the world a little better.