he just probably doesn’t know how to express his feelings, or even affection and just shows it through his anger
Anger and Sadness are like siblings.... if he didn't care he would be angry!
care he wouldn't*
I agree, on some cases, sadness and anger go side to side. But on this specific story and for a character as jaekyung, we all are aware that for the last plenty of chapters, he is lacking in capacity to feel sadness. Anger is his character if i must say.
Possesiveness and anger are siblings. And for a character as jaekyung, its obvious he views dan as something that belonged to him, not as someone he genuinely "cares" for. On some instances, it may seem like he cares for dan because of his intentions. But its like that isnt it? When someone is a jerk, all the bare minimum they did suddenly seems to be an act of pure and genuine care cause its very rare for them to not act like a jerk.
I understand that the last chapter seems to be that jaekyung cares, but its an act of possesiveness more than caring -- thats why his emotions are of anger, not frustration nor sadness.
What's so sad about this ending aside from dan still blaming himself for everything. Jaekyung is still shit and looks like he about to find and kill dan for leaving him, no emotional damage whatsoever in his part. Just pure anger issues.