I think Dan's grandma is going to die unexpectedly and then Dan finds out that Heesung saw what Jaekyung did to him. I think Dan's going to realise he has nothing left to lose and leaves. Jaekyung loses a fight cause he can't find a guy like Dan to break his jinx and starts to get desperate to get him back before he loses it all. Dan won't go back and Jaekyung delves into his past and why he's the way he is. He also learns about Dan's past and how his perceptions of him were totally off. Then he starts the long redemption arc bit and tries to woo back Dan after he realises he needs him more than to break the jinx.
Just my thoughts...what do y'all think?