My 21 Rescues Against Time and Space

I bought a magical watch that allows me to go back in time if I turn it counterclockwise! In order to save my lover and change my fate and hers, I traveled through time 21 times! However, a mysterious woman in black suddenly appears, following her like a ghost. Her appearance completely changed the fate of the three of us! Who is she? Why is she following me? What is my final fate? The final ending of this Rashomon-style time-travel suspense novel will subvert all your imagination!