Research on what makes a marriage work shows that people in a good marriage have completed these psychological "tasks":
Separate emotionally from the family you grew up in; not to the point of estrangement, but enough so that your identity is separate from that of your parents and siblings.
Build togetherness based on a shared intimacy and identity, while at the same time set boundaries to protect each partner's autonomy.
Establish a rich and pleasurable sexual relationship and protect it from the intrusions of the workplace and family obligations.
For couples with children, embrace the daunting roles of parenthood and absorb the impact of a baby's entrance into the marriage. Learn to continue the work of protecting the privacy of you and your spouse as a couple.
Confront and master the inevitable crises of life.
Maintain the strength of the marital bond in the face of adversity. The marriage should be a safe haven in which partners are able to express their differences, anger and conflict.
Use humor and laughter to keep things in perspective and to avoid boredom and isolation.
Nurture and comfort each other, satisfying each partner's needs for dependency and offering continuing encouragement and support.
Keep alive the early romantic, idealized images of falling in love, while facing the sober realities of the changes wrought by time.
Thanks to Judith S. Wallerstein, PhD, co-author of the book The Good Marriage: How and Why Love Lasts.