This story is so good, but why do people want a good end for? Sangwoo

I think what you pointed out just puts into perspective what an amazing job the author did to conceptualize the major themes in this story. In reality, many abusers are often victims themselves before they are anything else, but no experience they might have had will ever “justify” their actions. However, the reader can both acknowledge Sangwoo’s horrific actions and yet at the same time feel sympathy for him as a victim himself. This is the reality of human nature and how we view perspective. Humans often harbor a complex duality when it comes to weighing out the “good” and “bad” of others, and this story really challenges this concept as it progresses and layers on the plot.

I agree that readers can or may sympathize with Sangwoo after what he experienced throughout his life, starting from physical, mental, and sexual abuse that his parents did to him. I also felt sad when I learned about Sangwoo's past and the ending that Sangwoo experienced. However, what I find strange or problematic is the fans who justify what Sangwoo did because of his past, some even hope that Bum dies so he can keep his promise with Sangwoo, where Sangwoo said that if he dies, Bum must die. There are also readers who think that this ship should be able to continue together, even though they or more precisely Sangwoo will continue to commit mental, physical, and sexual abuse against Bum. In my opinion, sympathizing with Sangwoo is a natural thing because from the way the author writes, they wants the readers to sympathize, but that doesn't mean the readers can justify Sangwoo's actions because of sympathy

That’s um…what I said but yes there are some really odd fans out there who probably haven’t grasped the reality of these types of issues. Precisely why it should never have been categorized as bl or yaoi in the first place but what’s been done can’t be undone, I suppose :(

personaly I think this is just another point on "how the story is immersive" and so well writen! We, as spectator, are litteraly in their "relation atmosphere". You know that most of victim get attached to their abuser and really feel "in love" with them. Here I am not talking about the "Stockholm syndrom". A victim will adapt slowly little by little and create a "comfort zone" and little by little the abuse are getting worst and worst. They don't leave because they love, "he/she will change for me" in that story we are reacting the same way but "he will change for Bum" "Bum will be able to heal him" etc. We get attach to Sangwoo, we empathize with him, we are oki little by little with his abusive part and "forgive him" as if we were also "the perfect victim"

I say "we" because I speak like "in general"
There is so many story where the public ask for Mc to "gets his/her" freedom and a bad ending for the black flag (who didn t even do the 1/4 of what Sangwoo did) and you have story like this where you wish he could have a "good ending" kinda funny right XD This story is a master piece in its category, this is not only a psychological story, this is a psychological work that is also affecting the reader.

Right, fans like that, sometimes it's a bit scary and worrying

I wouldn t say scary but yeah you could be worry for them. If their reaction is already finding some excuses for a fictional abuser you can imagine some would probably react the same for a real life lover.