Sherin was the heroine who had an affair with the male lead, your fiancée. You were the villainess and was destined to die in the end. Sherin was once a selfish woman who didn't care about you and slept with your fiancée for power, but after you saved her from being killed. She started to have a realization of everything she has done to you. When you died, sherin did everything to bring you back, she wanted to apologize, and she wanted you to be happy. So, she turned back time.