I really dispute the premise of your thread. By the 1950s, moral degeneracy had already firmly taken hold. For a truly healthy marriage set up you have to go back at least 200 years, preferably 2000.

People on PPD really need to stop trotting out that tired old stereotype of the 50s as THE period of uber sexual conservatism. On both sides. The 50s had its merits, but it was a hotbed of crime and licentiousness compared with the 1890s, and a feminist-overrun liberal dystopia compared with the firm Patriarchal traditionalism of Roman or Victorian times.

A few key factors have been driving the overall decline of civilization for the last few centuries: democracy, racial/cultural heterogeneity, and dysgenics. All of these had already firmly taken hold by the 50s throughout most of the West.

In the 1950’s and earlier, how many of these marriages were unhappy and abusive environments.

Marriage has historically been abbout stability, economic efficacy and heirarchy. Its a rigid, contractual system of female slavery and enforcement of reproductive rights. Not happiness. Happiness is the whole problem with modernity. Its an indefinable abstract created by marketing gurus to get people to indulge their base impulses.

Are lower status men dropping out of society because they can’t get laid, or can’t they get laid because they have dropped out of society?

Lower status men dropping out is not the problem. Lower status men ARE the problem. The male population needs to be kept at around 40% that of the female population. Period. If a sufficient number of men aren't being killed, converted to eunuchs or enslaved, societal problems emerge.

Red Pill also emphasizes that duty sex for men is a third rate imitation of lustful sex, and for women, a chore to grin and bear.

Lustful sex is synonymous with submissive sex, for women. The problem isn't that marriage causes people who aren't "in lust" to be together. It's that the submission and slavery of women has been removed from the equation. If they aren't subdued physically they need to be subdued emotionally, which is honestly just much more of a headache than anything men in the ages of which I speak had to put up with. They could simply do what would nowadays be termed "marital rape" - laughable contradiction in terms btw - and their women would lap it up like the fuck dolls they all are. There is no hotter sex than being able to do whatever the fuck you want to another person, unfortunately, men in this age do not even have a frame of reference that can enable them to comprehend that. The very idea is outside their experience.