It was ethics of a different time.My four close childhood buddies from High School all have been married for more than half a century. Same ethos.
Mebbe it was something in the water.
I think back, and of my friends' parents' marriages, I can't think of any that were really more than pleasant.
But they all stayed together. Half of them had the parents with separate bedrooms. A couple didn't even really talk to each other. But divorce wasn't the fashion...the understanding was, "luuv" was nice, but marriage was more than what a couple of randy kids felt, years ago.
But today, commitment, duty, understanding one's place - be it, the breadwinner, or the homemaker, or even the middle-aged single person making a move on someone else who was inconveniently married...what you WANT, and what CAN be, we knew, back then, were often different.