My english is quite bad too, so don’t worry.
Well, Humber maybe loved Lolita, but he loved her in a sick way and the fact the he did the things he did turns him into a “monster” because he was a really bad person with her. He maybe didn’t want to ruin her life but he did! His intentions here aren’t an excuse, he did ruined her life and he knew he was doing it. And he killed Quilty because Quilty took his “pet” away. Maybe he loved her, maybe he was just obsessed and blind by her, but it doesn’t matter if he loved her or not, he was a monster with her, if he loved her he would let her go, he wouldn’t do all those horrible things to her and he’d do what’s best to her, not what he wants, not what he thinks it’s best, but what she wants for her own happiness.
But sure you can think like this, this is what I think, the same way that some people think that is a love story. We’ll never know the truth, so is good that we have differents points of view.
xx