https://www.mangago.me/read-manga/yuru_gyaru_take_nii_no_katabutsu_romanticist_kareshi/ but it's a spin-off of another manga
https://www.mangago.me/read-manga/kamisama_nanka_shinjinai_bokura_no_eden/ they did it before becoming a couple but I personally think they had a crush on each other way before that. You have to wait for vol. 4 though when they did it after becoming a couple and they do it like crazy

Yall anyone got stuff like
https://www.mangago.me/read-manga/koishite_kissshite_kanjaitai/
https://www.mangago.me/read-manga/itsuka_koi_ni_naru_made/
Where the uke and seme are already lovers after few chapters and been doing it cuz they horny since like high school??