You all who are angry are stupid saying they have no chemistry when it's been established way before when the Patrick Family first showed up, and when Jiwoo woke up after having his core shattered. Jiyoung came by to see him even if her schedule was packed and she'd be timid and all around him.
This is a snail paced romance and is NOT sibling whatsoever. Notice the two ACTUAL siblings and how they behave (Jisuk and Jiyoung) vs (Jiyoung and Jiwoo) they're completely different.
They're only two years apart people! She had to "grow up" faster to take over the company and such, but she is still young and is capable of having a crush. She's strong, independent, helpful, nuturing and thoughtful. She certainly doesn't have a "dry" personality. You're all just word vomiting what you read in the comments. So stfu haters.