Korean drama has 2 categories in general, 'romantic comedy' and 'melodrama'. When it's a comedy, you can be sure that the two main characters will ended up happy. But if it's strong on the drama/ angst, then it most likely ended with the MC dying.. There are also a few in-betweens, like for example, a detective/ revenge movie with a bit of romance and silliness, you can never tell for sure whether it would end happily or not