Okay, let's break this down.
The story is nothing new, if not even a little cliched and intentional on the angst factor.
What drew me in every week is the acting from both the leads. The tone had a somberness to it, and the color grading made it seem like it was going to have a sad ending.
But fortunately, it didn't. It was sweet in the end, but it didn't wow me because I've seen similar concepts being done way better before. Maybe if they extend each episode to more than 11 minutes, the plotlines and character development would've been more fleshed out. Right now a lot of their behaviors didn't feel organic, and resulted in more "telling" instead of "showing" (in this case a lot of clear, spelled-out internal monologues describing how the characters felt) This is not particularly actor's fault, of course, I just wished the transitions between each plot point was made more clear.
Kudos for K-drama's breakthrough in LGBTQ though. I applaud the bravery of the two lead actors and the production in general.