Self hate? Individualism? Consumerism? Personal liberty? Foreign Policy? Colonialism?
These are all topics on their own ... I'm not going to travel down that road.
I believe one of the reasons there is a relatively high percentage of single people living in single person households is because housing, like food, is much more affordable in the US than in many countries. From my own travels around the world it appears to me that grandparents tend to live with their children, single people partner with other singles as housemates and roommates, unmarried children still live with aging parents because ... housing is so damn expensive in much of the world - whether Europe, China, Japan, Latin America, etc.
We live in a much more mobile society.
As soon as kids graduate from high school or college they want to move out and have their own place.
I would suggest that more people who are feeling alienated might be happier if we create new kinds of "families" - situations where older folks are not isolated or there is no stigma of younger people living together as roommates or with their parents or married siblings. Remember the sitcoms "Threes Company" or "The Golden Girls"? Save some money on housing, and you'll have more disposable income on eating out, entertainment, travel, etc.
Just my opinion.