In their book, The Good Marriage: How and Why Love Lasts, Judith Wallerstein and Sandra Blakeslee have written about what comprises a good marriage. They believe there are nine psychological tasks that challenge couples throughout their lives together. These tasks are considered the building blocks of the marriage. The authors caution that, "If the issues represented by each psychological task are not addressed, the marriage is likely to fail whether the couple divorces or remains legally married". The authors believe that in a good marriage the couple is constantly adapting to each other and to the partner's changing needs and wishes. Here are the nine tasks they describe:

1. The first task is to detach emotionally from the families of childhood, commit to the relationship, and build new connections with the extended families.
2. The second task is to build togetherness through intimacy and to expand the sense of self to include the other, while each individual carves out an area of autonomy.
3. The third task is to expand the circle to include children, taking on the daunting roles of parenthood from infancy to the time when the child leaves home, while maintaining the emotional richness of the marriage.
4. The fourth task is to confront the inevitable developmental challenges and the unpredictable adversities of life, including illness, death, and natural disasters. in ways that enhance the relationship despite suffering.
5. The fifth task is to make the relationship safe for expressing difference, anger, and conflict, which are inevitable in any marriage. The task is to find ways to resolve differences without exploiting each other, being violent or giving one’s heart’s desire.
6. The sixth task is to establish an imaginative and pleasurable sex life. Creating a sexual relationship that meets the needs and fantasies of both people requires time and love and sensitivity.
7. The seventh task is to share laughter and humor and to keep interest alive in the relationship. A good marriage is alternately playful and serious, sometimes flirtatious, sometimes difficult and cranky, but always full of life.
8. The eighth task is to provide the emotional nurturance and encouragement that that all adults need throughout their lives, especially in today’s isolating urban communities and high-pressure workplaces.
9. Finally, the ninth task is the one that sustains the innermost core of the relationship by drawing sustenance and renewal from the images and fantasies of courtship and early marriage and maintaining that joyful glow over a lifetime. But these images, nourished by the partners’ imaginations, must be combined with a realistic view of the changes wrought by time. It is this double image that keeps love alive in the real world. (Wallerstein and Blakesless, The Good Marriage, pp.331-332)