It's a classic kdrama romcom, with all the tropes that make us both hate and love the genre. But this drama just nails those tropes, not overdoing them. The actors did a really good job, portraying everything down to single facial expressions in a way that the characters' emotions just come to the surface.
The pace is a bit slow, but that supports one of the best parts about the drama: it's a mature romance, not childish. It has it's cute jealousy bits and its posessiveness and all, but these don't overwhelm the relationship. The main leads are ready to give each other time, understanding, and seem to understand that their partner is a person in themselves with problems and a life that they need to sort out on their own to grow. The portrayal of this kind of non-toxic relationship is very rare and very precious in the kdrama world, and it especially shines when contrasted with the toxic relationship between the second leads, though that also changes for the better in the end.
The drama also deals with other heavy subjects like broken relationships (not just the romantic kind) and broken dreams, even suicide, but it does it well and ends on a positive note.
Definitely going to rewatch this in the near future when I need a feel-good drama.