My wife and I have a D/S relationship, but only when it comes to sex. We lead a normal plain vanilla life until it is time to play, then she becomes Girl and I am Sir. It took a while for me to believe she was so willing to submit to my sexual whims, but I have come to fully embrace it and we both fall into our roles comfortably. I feel it clear to my loins when I give her a command and she looks at my feet and says, “Yes Sir.”
We have a spare bedroom that is the “playroom” with various hooks in the ceiling, a single bed, an easy chair, and a bench - and a big drawer full of ropes and toys.
I can post details - and a surprise - if there is any interest.