i think many people know the plot of this movie, so i just want to share my opinion:
this movie really show the reality of couple nowadays especially the young one. because when someone will start have other commitment they can't balance between work and love. it just kinda confusing because both da eun and jang hyuk make mistake.
i think da eun start to cheat on jang hyuk after she abort the baby. i dont know if in korea, aborting is normal or not. i kinda pity at the other jang hyeok because he really love da eun but i dont think da eun really move on on jang hyuk( jang ki yong).