i think you’ll find small minorities of people - mostly liberals - are the reason for the hetero changes you mention. mostly communists and liberals peddling it as some kind of freedom. no fault divorce to empower and free women. corrupt regular men and women sexually was a communsit manifesto goal. the rank and file regular folks didn’t go for this crap nor were they pushing for it.
they are from the same mindset and militant culture the extremit homosexual advocates are from.
When sexual purity got winked and nodded at, soon the “gay” were asking “why not” to things they hadn’t even dared to dream about in the past. If you went back 2-3 decades you would have gotten incredulous stares from the homosexual crowd if you had asked it about marriage.