Honestly I didn't understand why Jojo dumped Sun-oh after all, and not figuring this, I couldn't enjoy season2 at all. Everytime Sun-oh went to talk to her the scene just got cut and they never actually talk about the reason!
I think people just accept misunderstandings as a part of every K-drama and directors don't see the need to explain many things. It's time for dramas to be a little more realistic.
And yes Sun-oh was immature but a part of why him and Jojo were able to understand each other was because of both having imperfections.That made their relationship more appealing.