First, Minjae was a minor at the time, second, the statute of limitations had already passed, third, the author shows us that without his son, he had no real reason to live, what kept him alive was the desire for revenge. But in the end, the father knew that he couldn't kill Minjae because he had grown to like him but he wanted revenge, he also felt guilty towards his son for having grown to like his murderer, the only revenge that could free him from all this pain was to kill himself. Why? Because he could finally join his son, he no longer had to feel guilty for loving his son's murderer, he didn't have to kill Minjae but he still took revenge by taking away from Minjae what he loved most, that is: HIM.
Who's agree?we can say that hyukjoon became a bit worthless because he became vindictive and just didn't do what was right,yes i know he lost his beloved son but can't he just think what's to do better. (which is to go to the police to report it or something i realy don't know) but human will still be human in the end.he chose to stab himself than to kill minjae because he had become close to him ,even if all he thinks about is revenge since they met but just so u know what if minjae hadn’t experienced all the painful past he had lol and you know that, hyunsook and him met in a nice way.
his obsession to his papa is in another level
may be because minjaee lived without getting what he wanted which is freedom and happiness and also love and also he experienced both physical and mental abuse that's why he turned out being selfish..but i like how taehyun took care of minjae..come on date me i'm better haha.