Add to the combustible power of passionate love the igniting agency of sex, and one produces an explosion which all institutional authorities have conspired to suppress for thousands of years. By and large the authorities succeeded. But no longer: Today passionate love is expected to lead to sexual union, perhaps even to marriage and family. The consequences for individual and society are enormous, and we now turn to that "igniting agency"—sex—to examine some of those consequences,"
source: Love, Sex, and Intimacy / Their Psychology, Biology, and History
Elanie Hatfield, Richard L. Rapson