Across many parts of the world, marriage rates are declining, prompting questions about the future of marriage as a social institution. At one level, this should not be surprising. Modern societies have witnessed profound changes in how people live, work, and relate to one another. Non-traditional arrangements have become increasingly common through cohabitation and other forms of partnership. Greater personal freedom and economic independence have enabled individuals to make choices that previous generations could scarcely imagine. Psychologists and sociologists have observed that marriage has shifted from an institution of necessity to an institution of choice. People marry not because they must, but because they believe it will enhance their lives. As a result, relationships today are often expected to provide emotional companionship, friendship, intimacy, psychological security, personal growth, and sometimes even spiritual partnership. In earlier times, many human needs were met t...