I can't think of any tbh. Maybe I'm just incredibly picky. I've yet to see a proper, well-developed happy couple with fluffy romance + consensual, kinky sex. There probably is one but I'm gonna be critical about it lol. The fluffy ones I know just do vanilla sex, the consensual kinky ones I know go straight to fucking so we don't see how their relationship developed properly. Other stories I've seen that are incredibly good tend to have drama that pulls away from the fluffy feeling.
There's this one in case you didn't know about it yet: http://www.mangago.me/read-manga/junai_drop_out/
Not that many chapters out yet, but so far it's pure fluff & kink (consensual at that). Enjoy!

Does anybody know any really romantic manga with a well developed and fluffy romance but with crazy hardcore sex? I'm talking sex in so many positions, with lingerie, or butt play ( spanking, butt pinching, groping). But I want there to also be lots of romance. Well developed relationship (has to be a reason the boys like each other) dates, hand holding, really romantic gestures. So love to hear your recommendations, my bl lovers.