I forgot name of manga the uke is bitch and fall in love with his Customer "seme" and seme give him money for his Services but uke It becomes sad, i think uke just a student but seme businessman and He has a mustache well I'm not sure
I actually searched on google the exact same thing you said and got nothin that seems to be the manga you are looking for I´m sorryyy TT
But if you want, I can reccommend some for you that have somewhat the same concept.~
But anyway if someone wants to chat here´s my insta: @namjoonerish reply