Yen found out that she had been into a traumatic incident five years ago that caused her to forget a huge part of her past. And that past included her marriage to Kim, the CEO of the company she was working for. She may not have recognized him right away, but something about Kim drew her emotionally to him.
But having already married Zed, an almost perfect husband to her except for his sexual flaw, Yen found it hard to let him go. She tried to convince her boss to move on and let her live in peace with Zed, but Kim wasn't the kind to concede.