Well, without having read the 'I failed to throw the villain away novel', it's hard to say precisely. However, based on the title, it could involve a protagonist who has a plan to eliminate or distance themselves from a villainous character. But things go awry, and the villain remains in the picture, causing trouble for the protagonist, their friends, or the world they live in. This could lead to a story full of conflict, suspense, and the protagonist having to come up with new strategies to deal with the situation.
Since I haven't read the novel, I can't say for sure. But likely there is a protagonist who is the one trying to throw away the villain, and of course, the villain themselves.
The villain with a crush might show conflicting emotions. They could be cruel in their usual actions but soft and vulnerable when it comes to the person they have a crush on.