I'm so glad he actually played the game. As for Jieun, I'm pretty sure she wasn't actually dating that as$hole. She must have had a story. Their chapter needs a proper closure though. It'd be nice if they have real closure.
Anyways, I'd prefer it if they don't get back together, even if there were reasons. It's just better that way. Ten years is too long and they've probably outgrown each other. It would also be nice if they become platonic friends instead.