Am not so sure but here are some answers
1. He doesn't trust kirin because that's how kangmoo's character is , he doesn't trust people no matter who because he believes that emotions sway people , kirin might one day feel guilty about what he did or feel sad about it and end up telling his police friend , i think this is a common belief for psychopaths to not trust people.
2. We already know that kangmoo is unable to feel certain feelings like love , rather than that he displays acts of possessiveness and ownership towards his partners , even a child who had no idea what love is feels irritated when his favorite toy gets taken away from him , or when they feel like someone might eventually snatch it away from them , i think that's why he behaved that way when kirin's ex showed up , he felt as if she could snatch him away
3. I dont know honestly but probably he did i dont remember
3. Yeah he did. In the first part of the story, when kirin recalls the past, he says to himself that when his sister got r**ed and killed herself, he was in the military. After knowing what happened to her, he got an early leave from the military.
I have a few questions here.
1. What did KangMoo mean when he said he doesn't trust Kirin in the ch 65?
He even said himself that Kirin is faithful and loyal when he is in a relationship with someone, so why?
2. And why did he get so insecure or jealous when he heard Kirin met a woman (a client) or when his ex wanted to meet up with Kirin? He also got very angry during sex when he heard Kirin and ex had done some oral play. Why was he so irritated and angry?
Again, he knows Kirin, the faithful boyfriend, would never cheat. So he thinks Kirin might leave him someday to be with a woman because he was actually never been gay/ with a guy (as his previous relationships were with girls) before he met Kangmoo?
3. And another one, did Kirin completed his military service before entering university? Was it ever mentioned by the author?