A veneer of sentiment may prevent these norms from collapsing—but only temporarily. The marriage culture, already wounded by widespread divorce, nonmarital cohabitation and out-of-wedlock childbearing will fare no better than it has in those European societies that were in the vanguard of sexual “enlightenment.” And the primary victims of a weakened marriage culture are always children and those in the poorest, most vulnerable sectors of society.

Candid and clear-thinking advocates of redefining marriage recognize that doing so entails abandoning norms such as monogamy. In a 2006 statement entitled “Beyond Same-Sex Marriage,” over 300 lesbian, gay, and allied activists, educators, lawyers, and community organizers—including Gloria Steinem, Barbara Ehrenreich, and prominent Yale, Columbia and Georgetown professors—call for legally recognizing multiple sex partner (“polyamorous”) relationships. Their logic is unassailable once the historic definition of marriage is overthrown.

Is this a red herring? This week’s Newsweek reports more than 500,000 polyamorous households in the U.S.