I think this is so fucking cute but damit Sangwoo don't hurt bum too much and Bum don't reject Sangwoo I mean come on !!! Aaaah, get together already !!!!
That's his JOB. Eak knew that when he entered the relationship. He's not doing it for pleasure, he's doing it because he's good at it and it pays well.
Yeah, probably 90% of the Yaoi population is with ya! LOL! I know I am....I'm too much of a romantic purist, but at least it is made clear he's in love with his innocent demon and the sex is just for work and not pleasure :D
They made an anime about them and the younger brother https://ww2.gogoanime.io/hitorijime-my-hero-episode-1