Marriage used to provide access to sex. Now it provides access to celibacy:

Marriage remains the most efficient engine of disenchantment yet invented. There is nothing like uninterrupted cohabitation and grinding responsibility to cast a clear, unforgiving light on the object of desire. Once children come along, it’s easy for parents to regard each other as co-presidents of an industrious little corporation. Certainly, all sound marriages benefit from sudden and unexpected infusions of good will—What luck! Here we are, so many years later and still as happy as ever! But the element that regularly restores a marriage to something with an aspect of romance rather than of collegiality is sex.

— Caitlin Flanagan, The Atlantic