Your entire premise hinges on the perception that she didn't consent to the sex, and I think initially in the beginning she was interested and did consent.

In a child liberation world, Humbert could have just made his intentions clear when he first arrived at the house, that he was interested in the young girl, instead of pretending to be interested in the mother. Then the relationship with Lolita could have developed out in the open with no secrecy and probably would not have ended up with such negativity attached to it, eventually causing all the bad outcomes.