Responses
I can't help but agreeing to your three comments here. I hope that before granny dies,she at least saw Dan genuinely happy. But if the situation will not allow,I hope that Jaekyung is already showing a change of his attitude towards Dan. I really hope for him to put down his ego and realize his feelings for Dan. It's very obvious that Jk is into Dan,I hope that he will not deny it any longer. Even Heesung in chapter 35 said so. I am patient for his redemption arc,I hope MINGWA won't disappoint us.
I feel like, deep down, Dan had a tiny bit of hope that maybe jaekyung went there for him because he had feelings for him. That's why we see Dan's pov of constantly questioning jaekyungs motive for being there. But when he heard him talk about the jinx you can clearly see that whatever hope he had just got extinguished as soon as he heard that word. You can almost see him die a little more inside.
This is just Dan's slow decent into severe depression. Granny's deteriorating health and then jaekyung being there being the way that he is, are what's needed to continue Dan's suffocating misery. Jaekyung has to continue being an asshole since Dan's misery hasn't been fully realized. When Granny dies , then that's probably when he'll start changing.