established couple from the start?

That's a sequel btw, in case you haven't read the first one it's called "on or off".


Anyway, here's one I can think of off the op of my dome https://www.mangago.zone/read-manga/nichijou_climax/

And this one that only just started so it doesn't have a lot of chapters yet
https://www.mangago.zone/read-manga/shamed_thanks_to_you/

Some more :)
https://www.mangago.zone/read-manga/bro_do_you_think_i_m_fat/
https://www.mangago.zone/read-manga/inukei_no_kareshi/
https://www.mangago.zone/read-manga/eat_me_up_my_husband/

And this one is really sweet and hot
https://www.mangago.zone/read-manga/koishite_kissshite_kanjaitai/

https://www.mangago.zone/read-manga/my_lovely_bunny/

https://www.mangago.zone/read-manga/shamed_thanks_to_you/

https://www.mangago.zone/read-manga/our_not_so_lonely_planet_travel_guide/