Chanwoo likes younger guys, that's why. And its because they are in S&M relationship, and its business.... eh
But didn't Chanwoo say "you'll do for now old guy" when they started the S&M thing? And people in S&M relationships can definitely date, so I don't see why that would mean that they aren't together :(
They're just fuck buddies, nothing more. They are in business. I mean its not prohibited to have a relationship on S&M partners. MD doesn't like to have relationships with his partners. And they agreed that they will only be a DS relationship. And their love lives will kept separated. Well I mean MD realized that he has feelings for Chanwoo, let's just be happy. :)
They weren’t dating?? I literally thought they’d been dating since season 1??? Why doesn’t Chanwoo wanna date MD anyways? MD is clearly in love with him, and I thought Chanwoo started liking him a lot, so why the heck are they not together?