L' s left buttcheek

hi guys! pls help me find this manga where the top became the “hero” of the story and he defeated the demon king, which is the bottom. and he had to marry and live with the demon king i forgot why. and there was a chapter where the demon king (bottom) transformed as a woman because he thought the top would be more into him. the bottom has black hair and the top has blonde or light colored hair,, this is all i can remember about the manga, i hope u guys can help!! (●'◡'●)ﾉ

the bottom have blonde hair and have two different eye colors, and the top have white hair and yellow eyes i think.. i totally forgot what that manhwa called but i hope this description will help me