"Destructive to marriage is the self-fulfillment ethic that assumes marriage and the family are primarily institutions of personal fulfillment, necessary for us to become "whole" and happy. The assumption is that there is someone just right for us to marry and that if we look closely enough we will find the right person. This moral assumption overlooks a crucial aspect to marriage. It fails to appreciate the fact that we always marry the wrong person.
We never know whom we marry; we just think we do. Or even if we first marry the right person, just give it a while and he or she will change. For marriage, being [the enormous thing it is] means we are not the same person after we have entered it. The primary challenge of marriage is learning how to love and care for the stranger to whom you find yourself married."