Some marriages require more togetherness; others, more independence. Each couple needs to have a sense of how these domains overlap. The trick is finding a balance of togetherness and self reliance that works for you.
One of the great joys of marriage is the ability to pool your strengths and special gifts. So if one of you is physical and the other intellectual, you can help expand one another's horizons. However, if one spouse is painfully shy and relies on the other to do all the talking, you're bound to feel an imbalance.
A similar kind of imbalance can occur when partners assume rigid roles based on gender: the husband who refuses to help with chores like cooking or cleaning because those tasks are "a woman's work" or the wife who refuses to pick up a hammer or screwdriver because "that's the husband's job." For a marriage to succeed in the 21st century, spouses need to be flexible in their roles, and willing to work together at all sorts of tasks.
Strong marriages are collaborative efforts in which both partners are dedicated to improving — as individuals and as a couple. Each marriage partner brings a unique package of strengths and weaknesses to the table, and each has a separate timetable for growth. But, if one partner's development or contribution is way out of proportion to the other's, the imbalance can undermine the marriage.