Following
http://www.mangago.me/read-manga/king_prince/
http://www.mangago.me/read-manga/mimitabu_no_riyuu/
http://www.mangago.me/read-manga/darling/
in my opinion this one also fits (playboy seme has sex with uke and slowly fall for him) though this one starts gloomy
http://www.mangago.me/read-manga/koi_no_mannaka/
kind of (playboy seme let his uke serve him but seme is also in love with uke)
http://www.mangago.me/read-manga/juusha_to_oresama/
a diffrent order (a couple, break up, seme plays around...)
http://www.mangago.me/read-manga/warui_yume/
Looking for some playboy seme who falls inlove with a sex friend uke