It's a manga where this guy, I think, was an otaku, but in college he changed his style and in his new group of friends there's a guy with glasses who was also an otaku incognito
With the description this is the one i got in my mind
https://www.mangago.zone/read-manga/zutto_kimi_no_turn/
“Play doesn’t mean sex” ehm no, he clearly says he's a SW so obviously play lead to sex otherwise he wouldn't be a SW. Just say you have a problem with him having a partner and still working but not something stupid like a SW who doesn’t sleep with clients
It's not so obvious in subverse (I mean there's even that one manga with a dom teacher/nurse doing basic play with sub students lol). So play doesn't always mean sex, but I agree that in this case it probably does ¯_(ツ)_/¯