This is honestly disturbing. Trigger warning is present almost in all chapters so read at YOUR OWN RISK.
Uke severely suffered abuse from childhood (from what he has been narrating that his father abused him as a child), this in turn, had psychological effects on him. If an abuse has been going on for a very long time, especially at the early stages of an individual's life, it is not easy to recover from it, and this has been clearly portrayed in the Uke's narrative. Haeyoung became his lighthouse as he was the only one he was able to go to and reach out to whenever he experiences abuses from his own father.
The beatings he unfortunately experienced somehow gave him this mentality that it's okay to go through such physical hurtings, Haeyoung obviously did the same physical abuse around the time his own father was also subjecting him to. The only difference that Uke seems to have distinguished between Haeyoung and his father is that, unlike his father, Haeyoung showed him bits of kindness that his own family failed to give.
I see a lot of people commenting that they don't feel bad for the uke, that despite him knowing himself he is subjected to abuse he refuse to leave. It is never easy to overcome trauma and abuse, Haeyoung became an important part of his childhood trauma, and this makes it very difficult for him to let go. He seemed to have highlighted in the manhwa that he's much better off going through the beatings than live a life without Haeyoung because that comfort would cause severe mental effects on him.
I am very much interested to see how this would pull through, but basing from spoilers from the novel that others has been sharing— I will need my snacks and tissues since shits not gonna be a smooth ride.