But in an era of peer marriages, in which both partners are expected to contribute and truck along, that mentality appears to have diminished. As noted by the National Marriage Project study, “Highly educated Americans have moved in a more marriage-minded direction, despite the fact that historically, they have been more socially liberal.”

“What happened?” asks the writer Claire Dederer in her memoir, “Poser,” which examines life as a new mother in Seattle. In the 1970s, “the feminists, the hippies, the protesters, the cultural elite all said, It’s O.K. to drop out.” In contrast, “We made up our minds, my brother and I and so many of the grown children of the runaway moms, that we would put our families first and ourselves second. We would be good, all the time. We would stay married, no matter what, and drink organic milk.”

Which takes us back to brownstone Brooklyn.

“One of the hardest things about divorce today is that you feel like you have to explain or apologize for it,” said Stacy Morrison, author of “Falling Apart in One Piece,” another divorce memoir. (Did anyone even write searing divorce memoirs in the ’70s?)

“The notion of divorce has become one of failure again,” said Ms. Morrison, 42, a resident of Park Slope. “It used to be, ‘You’re free, rock on!’ Now it’s, ‘You couldn’t make it work, you failed.’ ” Ms. Morrison described people’s reaction as “the two-second blink” when she says something along the lines of, “Zack is with his father today.”

Among a certain demographic, marriage is viewed as something that, like work-life balance, yoga and locavore cuisine, needs to be continually worked at and improved upon. When Ms. Dolgoff tells others about her divorce, their response, with disquieting frequency, is “Yes, well, marriage is hard” as in, “You knew that getting in.”

Blogs and child-rearing books suggest a subtle — and sometimes not-so-subtle — social pressure to tough it out. From the 1970s to the 2000s, the percentage of highly educated Americans who believe that divorce should be made more difficult rose from 36 to 48 percent.