The World After the Bad Ending

When I transmigrated, the protagonist was already dead.
Now, I have to protect the world after the bad ending.
So first things first, I became the enemy of the main heroine, who was on the brink of ending her life.
“I finally understand what all those things you said really meant.”
“I’m like this because of you, junior. Take responsibility.”
“I can only sleep when I’m next to you.”
…But for some reason, everyone is starting to act a little strange.