Watch the show from the beginning of episode 1 until episode 19, timestamp 27:15 (when the male lead (ML) and the female lead (FL) are on a rock, facing the sun, and screen fades to black - stop watching).
Then jump to episode 24, timestamp 3:42 (when the ML and the FL are walking on a bridge/walkway over water) and watch to the end.
The suggestion above will hopefully give you the best, happiest, and most consistent version of this show.
This is a school/youth drama that is worth watching for the beginning parts because they are SO GOOD, but unfortunately I think it's also one of those cdramas where the ending arc is ruined by horrible writing.
The stuff I think you should skip is absolutely pointless, feels like a completely different type of show, and makes the ML seem so out of character.
My personal rating for the show is 9.25/10 if you follow the above suggestion. If I were to include all the episodes, I would give this a 6.5/10.
