I've Become a True Villainess

I was just an ordinary graduate student.
I died and woke up to find myself transmigrated into a character in a reverse harem romance novel.
And not just any character, but Celia, the worst 'villain' from the original story!

At this rate, I’m bound to get killed just like in the original...
To avoid that terrible ending, I cleaned up the mess Celia had made in the past and
even promised to marry the second male lead, Callis.

But this second male lead... why is he acting like this ever since the original heroine appeared? Something is off.

But even stranger is the male lead, Leche.
Why is this guy approaching me?