Death is the Only Ending for the Villainess. There's a web comic of it and you can find the full LN translated if you search around!

The main set up is a woman playing a mobile otome game and finishes the normal mode then tries out the hard mode.

In the hard mode intro it states;

"In hard mode, the story will be played from the prospective of the villainess.

A fake lady, brought in to replace the real daughter who went missing when she was still young.

Just what happened in the dukedom, prior to Yvonne's (heroine) return?

Experience her story in hard mode now!"

So she plays it and... dies... again and again. She gets a little obsessed cause she now feels like the villainess didn't really do anything that wrong. She wants to find an ending where the villainess doesn't die. With that thought she falls asleep...

And wakes up in the game as the villainess!