I don't think there has ever been a stigma amongst the rich and upper class.
I know that I perceived a stigma when I was a kid. My parents had separate beds (same room though) and when friends came to my house and saw the bedroom they universally thought it was weird. (In fact, I tried to keep the door closed so I wouldn't have to deal with that whole discussion.) My parents divorced, but I dunno whether the separate beds had anything to do with anything. My dad now sleeps in a separate bedroom than his current wife, and they seem to still be going strong. (About 14 years for them I think.)
Lol! Oh my yes.
In my solidly middle class childhood milieu, I can recall my absolute amazement and shock when I saw the sleeping arrangements of the parents of one of my friends....SEPARATE SINGLE BEDS!!!!!
With a CABINET between them, so they could not be easily rolled together.
This, although I knew full well that my parent's marriage was a sexless, cold horror. But at least they slept, albeit miserably, in the same bed.
Mind you, it was equally stunning, although in a different way, when a friend and I went to get something from HER parents' room, and accidentally opened the "toy drawer".
Inside was evidence of actual sexual activity!!!! LUBRICANT!!! CONDOMS!!!!