
On another note, I don't get why people keep thinking Ido is being nonchalant. He's withdrawing into himself, not being cold. Those who deal with depression and are in the thick of it will always view the silence of others as rejection. Sejin is depressed and Ido is depressed. They're not communicating and they're not understanding one another, getting what they need or trying. They're both too worried about getting hurt or hurting the other person. So, no Ido is not cold or cruel right now. He's withdrawn and scared.

Learn some etiquette and be nice. There's no need to be mean. Especially to people you don't know. I have severe depression and anxiety and I'm also extremely well-versed in psychology. While I may not know everything, I do know from personal experience as well as watching other's behaviors that this is exactly how they act when they're depressed. If you don't know, or you suffer from depression but don't act this way, then either don't comment, or say something along the lines of "i have depression but I don't act that way". But there's no need to be rude. You have no idea if something mean you say is the last straw for someone that sends them over the edge. I'm serious. You really don't. And that karma will come back st you, trust me.
Maybe Ido has been wanting revenge this whole time. What if he's been building Sejin up only to kill himself in order to make Sejin feel the way he felt in their past loves? Or he could be hella depressed and coming to understand why Sejin did what he did. Guilt does a lot of horrible things to a person. I hope neither of these options are true, but who knows. I've got a bad feeling, though.