Listen, DO NOT waste your time on this movie, GO READ THE WEBTOON/MANHWA INSTEAD!
Okay that was a bit harsh - the movie is not bad as one of those feel good rom-com which you won't even remember about next week. The story makes sense and everything, and I really appreciate that Netflix didn't do an aggressive Fifty Shades of Grey which screams "sexy bdsm!!!"
But the movie is seriously horrible comparing to the webtoon. I feel very sorry for the original author. After I finished the movie, I didn't feel like reading the webtoon at all because the movie was so... mediocre. I'm extremely glad that it popped up in my webtoon recommendations anyways - because it was so amazing and I finished 146 chapters within 2 days.
Without spoiling the original story, I just wanna say go read the webtoon. Don't worry if you've already watched the movie! You would find first 20 chapters somewhat resembles the movie - but as you go on, you would find yourself in a completely new story. This is because that the movie has basically cut out all the side characters/storylines, made major changes to protagonists personalities, and ignored all the small yet important bits of how the couple's relationship was developed. The way that the relationships were portrayed (between lovers, friends and families) in the original work feels authentic (as in, no weird drama), delicate and heartwarming - and none of that existed in the movie. Oh, they also did Ji-hoo dirty by making him look like a terrible person.
So yeah, don't miss out on the webtoon because of the movie. It's not some average rom-com like the movie - romance manhwa like this are so difficult to come by.