I so very very agree with you!
oh come on! he was raising him to be his successor and bitch, and Mookyul was aware of that. Reading the main story, you realize that Mookyul was aware that he was his whore and he wanted to be. He just quited when he didn't wanted to anymore. As for the "old man" is kinda funny, because he hated the fact that he was captivated by the kid and did everything to keep him. He didn't calculate that the "dog" wasn't going to stay loyal if that "dog's" heart was captivated by another "master" ;)
when you take in a child, you do not start a sexual relationship with said child. even if the child consents to it, it's still statutory rape.
For me, it's easier to take these types of stories with a grain of salt (since I know they are fake and no child was actually hurt during the making of this manga). Outside of that fantasy world, it is the worst thing you can do to a child, as that child may also grow up, and do the same to another, then they grow up and do it too, and start a terrible cycle. It's not always about knowing what is right and wrong, because you have to have someone with integrity teach you that in the first place.
There are things in Yaoi manga that I find to be tolerable but in all honestly the one part of the story that I couldn't handle at all was something that was deeply integrated with the main love interest. The old man and his relationship with Mookyul was absolutely garbage. He maybe be portrayed as some handsome President but I swear, I wanna destroy his character. First of all, he adopted Mookyul when he was in elementary school. Second of all he started a sexual relationship with the kid he raise. I don't know when he started this relationship with him or how long it's been going on so it disgusts me. He's literally an adult do not take advantage of children. The way that Mookyul reason with Ewon that this person was his father and that it was normal relationship was upsetting. His only guardian raising him in way that he believe relationship like this was normal, that it was okay. Disgusting. I don't care if he truly loved Mookyul as a son but you never take it to that level. You don't fuck with your foster son, you douchebag.