It is amazing how short our collective memories are, and how "we" have forgotten the impact of the biggest medical/cultural advance of the mid-20th century: safe, painless, and reliable artificial birth control, often referred to collectively as, "The Pill."
Ignoring the degenerates on the margins, for most of America (and Western Countries generally), before the advent of The Pill, sexual activity had to be controlled; the biological father was PRESUMED to be responsible for any offspring, whether the couple were married or not. Women could not enter into a "serious" career unless they made on overt choice not to have children, and convinced the significant others in her career that the choice had been made. Otherwise, why would you take a woman into a serious management track position? It would be stupid. She could render the whole thing worthless the minute she got pregnant. And it wasn't just the short period when she would have to be off to have a baby; you knew that she would be the primary nurturing parent for the following 20 years or so, thus rendering her an uncommitted, unreliable employee for that entire period. Every time that kid got sick or had any other significant problem, the mother would be off work tending to it.
The Pill completely changed the focus of responsibility from the man to the woman. Since she had the ability to prevent pregnancy, if she DID get pregnant it was "her fault." Although the law hasn't changed substantially (buttressed by DNA testing in recent years), in the popular culture, the "sperm donor" has no obligation to marry the mother or to play a significant personal role in raising any offspring.
Prior to 1970, any woman in the U.S. could look the world straight in the eye, and say, "I choose not to work." Her life goal could be to find a "responsible" husband who would take care of her and their joint offspring for the rest of her life. And that was a perfectly legitimate - even honorable - choice for a woman to make, even if she were a college graduate.
But now, a woman is expected not only to be a baby factory, but also to support herself, and NOT let the introduction of a child or children significantly impair her career! If she starts off with the thought that she will "not work (outside the home)" she is considered lazy and lacking ambition - or worse.
And if a woman is a baby factory and a productive person economically, then what more is a husband but an optional doo-dad? If he pleases her in some ways, that's fine, but she can get along fine without him, if need be. If she chooses to have a kid or kids on her own, the culture supports the choice, her employer is almost forced to support the choice, her family (such as it is) will not condemn her and will support her choice. Having a husband is purely an option.