I think you'll never be alone in your sickness, Rourou. :)
On my part, I hate to see things I love end, as much as I hate the final page of a book, or say goodbye to my friends when they leave after a visit. I could say that I hate to say goodbye in general.
Asian drama wise it has happened to me with Liar Game, Long Love Letters, Coffee Prince, Secret Garden, and lately King2Hearts, to mention a few.
Finding another drama soon after one I loved finished, does not work for me at all. On the contrary, I realized I often dislike whatever I watch soon after: I compare, which is never a good idea.
On the other hand, because what I feel for the characters is usually very similar to a romantic crush - and has the same distressing symptoms - I have followed an actor (or actress) in another role of his. It worked only in part, because the one I fell in love with was obviously the character, not the actor.
Furthermore, I'm an avid re-watcher/reader, so I inflict myself the torture of fuelling my obsession.
The only solution for me is let time do its wonders, just like after a heartbreak. In the meanwhile, I can cope with some completely different dramas that don't require a deep emotional investment: action, goofy comedy or episodic show. Or another country/language, which gives me the impression I've gone on a holiday elsewhere for a while. :)