In "I Have a Lover" Kim Hyun Joo revealed the reason that she did not look for her past.
On the episode of SBS "I have a Lover" (script Bae Yoo Mi, director Choi Moon Suk) broadcast on October 17th, Choi Jin Un (played by Ji Jin Hee) embraced Hae Kang who shed tears and was tying the shoelaces of Do Hye Kang (played by Kim Hyun Joo).
Afterwards, the two people sat next to eat other at a café. Jin Un asked Hye Gang whether she remembered this. At this, Hye Gang said, "It happened four years ago. I don't know the reason. I just woke up one day and there was nothing in my memory.
Meanwhile, "I Have Lover" is about a woman who lost her memory met her husband that she hated. With that, she falls in love with him and at the end of a very destined meeting, she meets her long lost twin. With that, the lives of the two are reset.