It's so creepy because you read the repeated sexual abuse of a minor through the eyes of the perpetrator who continuously justifies his acts and misrepresents Lolita's reactions. He's a very unreliable narrator. First he even becomes her stepdad to have better access to her. Then her mother dies, through a car accident just before she can call the police on him. Again this is recounted through Humberts eyes, so I'm thinking it was actually murder.
I haven't finished the book yet, it's kind of hard to read. It's been a few years, and I should be somewhere in the middle IIRC.