Watching the movie after the series is a bit strange. They changed a lot and compressed a lot and took out a lot. I know the story is based on some famous novel(s) so now I'm wondering what's in those novels because these two characters in the movie are giving me different vibes from the series, so my advice would be to separate them completely. It's just the bare bones of the series. There's a lot more of and about her here, whereas in the series she gets married pretty quickly and mostly disappears and there's less of him here. Be basically has two relationships, one of which is completely different from the series, although it's the guy he's kissing while meeting her. I am a little baffled by these changes and I don't understand the reasoning. But yeah, its heart is in the right place and these two here shine through the screen and their friendship is epic, which it wasn't in the series, so it is a nice watch on its own. It feels like it shows a lot more of the homophobia in Korea, but maybe it feels that way because it's compressed. He is a lot more unhappy and guarded than in the series, where he had a more bubbly personality, albeit still closeted. Nam Yoon-su ruined me.
So yeah, I keep picking at the differences, although I said I shouldn't because it doesn't help. It's a good movie. I enjoyed it. But damn Korean men are scary. And they gossip a lot and they bully and sl*t-shame. In and out of the office, at school, etc. Geez...