Its probably the size of THAT penis that is a pain in the ass
Doyoon said that he's unfittable to extract the sex essence of certain people, and after doing it once with thr director, he discovered the director was one of those people. Doyoon wanted to stop it after realizing that, as his hunger would never be satisfied properly and his condition would not stop to worsen, but the director had already targeted him and made him his boyfriend, almost threatening to fire him if he didn't accept. Doyoon doesn't love the director and just wants to get out of this mess, thus he tries to hook up at least once with one of his expartners that could satisfy his hunger... It's not all over the place, Doyoon simply needs to get his resignation papers and find a fittable partner. But he's dumb.
The art is Flawless and absolutely beautiful... But Doyoon's character is the most confusing/confused character ever. Since day 1 is problem was being hungry and not getting enough essence, the story basically revolves around that. He lived his entire life on essence. So it annoys me that he always complains and acts surprised when the director wants to have sex with him. Which was just 2x.. TWICE! He's always saying No! Or "When will it stop?" .... Its better to just own and love having sex than be this confused. Then after they've done it.. he's gonna complain that he's hungry again. Whatever.... He complains alot.