The decline of religion also probably plays a role here. You'd have a hard time blaming that on the end of the gold standard.
I mean, sure, economics almost certainly plays a role. But it's not the sole cause.
Although, people could maybe speculate that dual income families also became a necessity as a result of worsening economic conditions. I don't know.
(And for the record, I'm not using feminism as a negative word here.)
The industrial and agricultural revolutions have only recently allowed most of us to live in cities and do other work than trying to grow enough food to survive. And so new ways of living are arising that work for people in the new era.
We are probably going to see a lot more variety in living arrangements before things settle into a new normal. I wish I could be around for the next couple hundred years to see it all happen!