An alternative theory, and I think much larger reason for the destruction of the family unit is that individualism was heavily marketed by mainstream media through the 20th century. People shifted their wants and desires in marriage from one of creating a family unit to that of finding personal enlightenment.

The excellent documentary The Century of the Self covers the evolution of marketing, the baby boomers and the psychology behind individualism:

https://en.wikipedia.org/wiki/The_Century_of_the_Self