Hanna, I too read the Sandra Tsing-Loh piece in the Atlantic , and I think she's missing part of the point. It's not modern marriage that's the problem , it's modern child rearing. Motherhood and marriage are inextricably linked in Tsing-Loh's piece, and while she never explictly says it, she chooses modern motherhood over her marriage:
Given my staggering working mother’s to-do list, I cannot take on yet another arduous home- and self-improvement project, that of rekindling our romance. Sobered by this failure as a mother-which is to say, my failure as a wife-I’ve since begun a journey of reading, thinking, and listening to what’s going on in other 21st-century American families.
But even though Tsing-Loh complains about the "staggering working mother's to-do list," she refuses to get a nanny because she "secretly worried that using domestic help was exploitative"; she describes children with an "extraordinarily challenging roster of extracurricular activities and a quarterly testing schedule." And everyone seems to want to have sex ... until children come along.
This is obviously a debate of privilege, but all the women Tsing-Loh describes in her piece can afford a nanny, a housekeeper, or a baby sitter. I don't think it's so much that the idea of a life-long partner is out of date. It's that women need to hand over some of the child-rearing duties, and perhaps let little Timmy play baseball in the yard rather than signing him up for the elite traveling team; to let little Timmy study for his tests on his own, rather than getting so freaked out about his "quarterly testing schedule." If those things are more important to you than working on your marriage, that's your choice, but it's not the fault of the institution.