[chung8123]

It has not been forever true that households have had two incomes. Now it is common.

[zeroonetwothree]

Well, only because one of the household did a huge amount of unpaid labor. A lot of which now has been replaced with paid labor (child care, restaurants, house cleaners, and so on).

[OGEnthusiast]

I meant it's been true forever that people with partners generally have a financial advantage over single people. (Even if they're not in a two-income household.)

[fh973]

What has changed is that dual income became the norm, and is no longer an advantage, but mandatory to compete on the housing market.