From The Way We Never Were: American Families and the Nostalgia Trap by Stephanie Coontz:

Like most visions of a "golden age," the "traditional family" my students describe evaporates on closer examination. It is an ahistorical amalgam of structures, values, and behaviors that never co-existed in the same time and place. The notion that traditional families fostered intense intimacy between husbands and wives while creating mothers who were totally available to their children, for example, is an idea that combines some characteristics of the white, middle-class family in the mid-nineteenth century and some of a rival family ideal first articulated in the 1920s. The first family revolved emotionally around the mother-child axis, leaving the husband-wife relationship stilted and formal. The second focused on an eroticized couple relationship, demanding that mothers curb emotional "overinvestment" in their children. The hybrid idea that a woman can be fully absorbed with her youngsters while simultaneously maintaining passionate sexual excitement with her husband was a 1950s invention...