"In a cruel cultural twist, just as we have increasingly looked to our marriage to help us fulfill higher-level needs, we have decreasingly invested the time and energy required for the marriage to meet these expectations. According to one major study, the amount of time that childless Americans spent alone with their spouse declined from thirty-five to twenty-six hours per week from 1975 to 2003, with much of this decline resulting from an increase in hours spent at work. The decline for Americans with children at home was from thirteen to nine hours per week, with much of it resulting from an increase in time-intensive parenting."

From: "The All-or-Nothing Marriage: How the Best Marriages Work" By Eli J Finkel