So far in the show, she's a bright, young girl who's not as shy as her mother makes her out to appear. But, she's apparently got this huge secret. Her mother kept on repeating to her new Son-in-law, Sang-hyun, that "this happened before" and that "she trusts anybody", which is a problem. So, I'm guessing that they'll explain this in future episodes, but I'm really curious in the meantime. And perhaps this is the "event" that Eunjoo was talking about which led to the distance between her parents??
This is one of the interesting things about Korean dramas to me--the way they begin with portraying situations that have been going on for years and pick up right before those situations start to change. The estranged husband and wife have been rubbing along for ages like that, but now the wife is starting to question things. And the woman who runs the publicity firm has been trying to catch the widower's attention for years, but now she's taking the bull by the horns.