This was bittersweet. The girl doesn't remember him or she looks like his past lover? I also have my own version of ending when I'm not satisfied with the original ending of a drama >_< (this happens often!). Though I haven't seen the web drama, I'm sure your version is better.
I never watched this drama but this was very nice. I'm kinda guessing that the girl is someone that resembles someone he knew or that she lost her memory. Just 100 words and the story can make you try to think 10 different scenarios lol.
First off, congrats on being the first day of the advent calendar!
Now to the review :) This is a cute drabble, that could easily fit into a story of a bigger scale. However, my biggest issue was that because it is linked to another work and I have not seen it, it made me confused as the assumption is that the reader would know the back story.
All that being said, I like your style of writing and hope to read more of your work :D