If you were to randomly ask 100 people in the US, "why do couples marry?" it is a safe bet that at least 90 of them would reply, "People marry because they fall in love."
Most of us find it hard it imagine a marriage being happy without love; for the same reason, when people fall in love, we expect them to think about marriage.
But is the decision about whom to marry really just a matter of personal feelings? There is plenty of evidence to show that if love is the key to marriage, Cupid's arrow is carefully aimed by the society around us.
Society has many "rules" about whom we should and should not marry. In all states but Massachusetts, the law rules out half the population, banning people from marrying someone of the same sex, even if a couple is deeply in love. But there are other rules as well. Sociologists have found that people, especially when they are young, are very likely to marry someone close in age, and people of all ages typically marry others in the same racial category, of similar social class background, with about the same level of education, and with the same degree of physical attractiveness. People end up making choices about whom to marry, but society narrows the field long before they do.
Sociology - John J. Macionis 12th Edition