I didn't like the forced living together in Episode 1. Where does something like this fly today? Even if you would like that person, you would not start living together out of the blue. The rest of the story for the main couple was ok-ish. The side-couple was more or less wasted with too little in depth storytelling. They should have the flashbacks for both couples in the beginning which would have helped tremendously. The drama of Kim Jin Woo daddy was there to support the point that he's afraid of not connecting with the people he loves. Contrary he did connect with the girl in Ep 4 which didn't make much sense to me. If you are a loner, reclusive you don't connect with people in no time.
I wish they would have just concentrated on the lead couple and had a series for the side couple, maybe with even only 6 episodes per series.
The friendship between Jung Ki Sub and Choi Balg Eum was the highlight of the series for me. Overall it was an ok-ish series, not earth-shattering story-wise with some fluffy moments, but also not bad.