She posted on the show’s message board on the 22nd, “It was confusing to take on this character of Hye-rin, who even I can’t understand… As an actor in this drama, I feel a duty and responsibility to stay with it through the end. But I’m sorry to tell you I can no longer act in this situation, feeling this way.” She added, “I don’t want to act saying and doing such illogical, out-of-character things in this role that makes me look like an idiot.”
Apparently the production is currently consulting with the writer on how to write her out of the show; Lee will probably appear for a few more episodes. (Who wants to bet that insulting the writer in her goodbye message isn’t the best way to get a glorious send-off?) Her action has spawned a lot of speculation among fans, some who would like to be understanding and others who decry her act as irresponsible and unprofessional.
source: dramabeans