Consumerism is certainly a factor, but that factor was largely the product of the rise of TV and the effectiveness of TV advertising. TV killed much of what was good about the USA by anesthetizing our imaginations and undermining our health.

But the nuclear family, which you may recall was the sad remnant of the large multi-generational farm families pre-WW2, was doomed by the pace of change and the stresses of an economic system being crushed by income inequality. Two adults are simply not enough--even if one of them is at home full-time--to meet the physical and emotional demands of a household with children.