I, the Substitute, Escaped, and He Regretted It Too Much

The Female Protagonist Misunderstood the Male Protagonist, and After Killing the Male Protagonist, She Learned the Truth and Regretted It, Asking for Forgiveness.

I want to watch something similar to "Male Supporting Actor: After I left, the heroine regretted it beyond measure!" Book.

The heroine was used as a substitute and left after knowing the truth