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.