The name of the drama I was looking for is Secret Love Affair. Received a 8.8 at Daum, but don't know if I can trust it. I remember glancing through the first episode and really liking it, it seems one of the very first actually mature/serious Korean drama I've seen.
EDIT: Top page, have nothing to add here except old gifs.
EDIT: Top page, have nothing to add here except old gifs.