In his weekly column for National Review:

The great divorce revolution of the 1960s and 1970s has faded. The great cohabitation revolution has begun.

The divorce rate for married couples with children is almost back to the levels of the early 1960s, before the run-up that crested in the early 1980s. Considering the decades of social turbulence buffeting the institution of marriage between then and now, this is a notable restoration.

But it only means that marriage is unraveling in a different way. According to a new study by the Institute for American Values and the National Marriage Project at the University of Virginia, cohabitation has increased 14-fold since 1970. About 24 percent of children are born to cohabiting couples, more than are born to single mothers, while another 20 percent experience a cohabiting household at some time in their childhood.

... We want to believe that all relationships, so long as they are loving and well-intentioned, are equal. It feels like an offense against 21st-century mores to say otherwise. Who are we to make invidious distinctions among loving adults? But there is simply no substitute for marriage, for the relative stability and commitment it provides, and for the environment it creates for children.