The complexity of Lolita and Nabokov’s moral intention

1/ Consider Lolita:
- It is narrated not by Lo, but by Humbert Humbert;
- who is manipulative and extremely charming, with his intelligence, intellect, gift for language and wordplay, and sense of humour;
- And above all, Lo is not “pure”.
Imagine a Lolita told by Lo, or a Lolita in which Lo is a pure, innocent child. That would have been a lot easier—the victim is clear. Instead, Nabokov went for something a lot more complex and tricky and not so black and white. Some readers, apparently not understanding literature, think that because Lolita is narrated by the paedophile, it must either be a child sexual abuse manual or a condonation and justification of it. Some readers, perhaps not aware of what a genius writer is capable of, think that because Humbert Humbert feels so real and convincing, it must be autobiographical. And then there are readers who, confused in matters of morality, fall for the trap and allow themselves to be manipulated by Humbert Humbert—a friend of mine, for instance, has just said that maybe Lo wants to be a victim, like she’s “asking for it”.
Despite Nabokov’s claim that Lolita “has no moral in tow”, it is not devoid of moral intention.
Lo is a victim.
She is 12.
That Lo is sexually precocious—a nymphet, is beside the point.
That she is far from “pure” is beside the point.
That she has a crush on Humbert Humbert and jokes around with him is beside the point.
A man in his late 30s cannot say about a 12-year-old “But she seduced me!” as a defence. Worse, he’s in the position of a stepfather, and a guardian. Even though the story is seen from the point of view of Humbert Humbert and Lo is hardly there, now and then Nabokov slips in some details to show that Lo is alone and helpless, that she is suffering, that she doesn’t want to be with Humbert Humbert. The rapist himself has remorse. In the last meeting, he knows that he broke her life. He also writes “Had I come before myself, I would have given Humbert at least thirty-five years for rape, and dismissed the rest of the charges.” 
Humbert Humbert is a paedophile, an abductor, a manipulator, a child sexual abuser—he is a rapist. Period.

2/ Another friend of mine says that some girls are much more mature than their age. I have no idea what that even means. Lo is 12.
12.
That reminds of another question: imagine that Lo is 15 when meeting Humbert Humbert the 1st time. The matter would be less clear, on the surface. In France, Denmark, Sweden and some other countries today, 15 is the age of consent. However, Humbert Humbert would no longer be a paedophile but that doesn’t change the facts of the case: he abducts, deceives, manipulates, controls and rapes Lo.

3/ Can we and should we forgive Humbert Humbert? 
This is not an easy question to answer. Nabokov is so often praised for language, style, wordplay, sensory descriptions, patterns, hidden games and allusions that people “forget” his understanding of psychology and genius for characterisation. Nothing is black and white in Lolita, and the characters are complex and multifaceted. Take Charlotte Haze. We dislike her for her vulgarity, her shallowness and thoughtlessness; then the next minute we pity her for having delusions and being deceived by Humbert Humbert; then even though it’s brutal of him to speak of her as fat Haze and all that, it’s hard to like her when she’s such a careless, selfish and insensitive mother who is sometimes just mean; then again we feel sorry for her when knowing about the dead boy and getting a glimpse of her sorrows; then the next minute we see her being harsh and mean to Lo; etc. And in the end comes the painful moment when Charlotte discovers the diary  and sees all illusions shattered and then gets killed by a car. I strongly dislike her as a mother, but at the same time deeply pity her. 
It’s a lot more complicated with Humbert Humbert. He mocks and is contemptuous of almost everyone. He lies and manipulates people—Charlotte Haze, psychiatrists, John and Jean, Shirley Holmes (at Camp Q), Lo, etc. and also the reader. He marries a woman for whom he has neither feelings nor respect, to be close to her prepubescent daughter, seeking the role of stepfather and then guardian with the sole intent of abusing it. He lies to, abducts, manipulates, controls and abuses Lo sexually and emotionally. He is a paedophile and child rapist—that is clear. And yet, the book is a confession. Humbert Humbert is a villain deeply aware of his own villainy. He knows what he has done—that he is a monster and has broken Lo’s life. He knows that nothing he does can change the past, but has remorse and seeks to do something for her at last. The book is a public confession, an examination of everything he has done, and an attempt to restore life to Lo as a way of atonement. 
Here is a much better post about the same subject—D. G. Myers on Lolita as the enactment of moral experience (and why he called it the greatest novel ever written in English). 
So can and should we forgive Humbert Humbert? Well, I don’t really know.