This drama is the king and queen of flashbacks. It would be twenty episodes instead of forty if all the flashbacks were removed. Not only flashbacks but the same ones over and over again. Plus no kiss for the leads. Other couples yes but not for the leads.
Does this drama really need forty episodes that are over forty minutes long? There's almost always a lot of drag in later episodes with fillers I don't even watch.
https://kisskh.me/Drama/My-Blue-Summer/Episode-1?id=6606&ep=112683&page=0&pageSize=100
https://www.youtube.com/playlist?list=PLm6KaO9p7tM9p542PiIlJ8c9Xxai5dh9j