The central twist of "Marry My Husband" is not just that Kang Ji-won travels back in time, but that her manager, Yoo Ji-hyuk, did as well. In the original timeline, Ji-hyuk had secretly been in love with Ji-won. After her death, he confronted Min-hwan and Su-min, got into a car accident, and died, only to also wake up in 2013. This shared secret, revealed in Episode 6, fundamentally changes the series from a solo revenge mission to a collaborative effort.
A key rule of this universe is that fate is transferable. Ji-won's initial death by being pushed onto a glass table by Min-hwan is transferred to Min-hwan himself. He is killed by Su-min, who pushes him onto a glass table during a fight after she discovers his affair with Oh Yu-ra. Similarly, Ji-hyuk's fated death in a car accident is transferred to Oh Yu-ra, his obsessive ex-fiancée. She dies in a fiery car crash while trying to flee the country after her crimes are exposed. Ji-won's stomach cancer is initially passed to her colleague Ju-ran, but because Ju-ran discovers it early thanks to Ji-won's intervention, she survives. Su-min ends up imprisoned for Min-hwan's murder and the attempted murder of Ji-won, inheriting a miserable fate of her own making. The finale shows Ji-won and Ji-hyuk happily married with three children in 2023, having successfully rewritten their tragic destinies and built a beautiful life together.