I find it weird that everyone is saying Boo Hye Ryun is awful; he knew what he was getting when he married her. Pan San Hun knew how she was when he married her, he should have known better. Marriage is about compromise, and she was never about it, so he is just as culpable.
Totally agree with everything you said, a different female lead would have enriched the story. I felt like she was too immature for the role. Both characters had experienced pain, and suffering, but she was running around acting like she was 18, it was weird.