A curious thing happened in the Beltway last week: for the 48 hours surrounding two landmark gay marriage Supreme Court oral arguments, the millennial political class’ collective Facebook feed blushed bright red. Obama-handshake profile pictures gave way to a sharp crimson square designed by the Human Rights Campaign’s marketing department.

Between torrents of memes and legal commentary on Ruth Bader Ginsburg’s skim milk analogy, Samuel Alito’s rusting Burkeanism, and Elena Kagan’s “batting average,” another item, a report about adults turning to cooperative households to save money, passed without remark in liberal circles.

Two million Americans over the age of 30 now live with a housemate or roommate, and shared households make up 18 percent of U.S. households – a 17 percent increase since 2007.

One group of women sold their homes and bought a house together in Mount Lebanon, Pa., after they all got divorced.

“It made amazing economic sense,” said one of the women, Jean McQuillin. McQuillin, Louise Machinist and Karen Bush call their home a “cooperative household.” Each woman has her own bedroom and bathroom, and they share the common areas of the house, chores and expenses.