Is Humbert Humbert a reliable narrator?

Humbert Humbert is not a reliable narrator. Part of Vladimir Nabokov’s purpose in Lolita is to construct a narrative so full of twists and turns that it forces the reader to confront not only Humbert’s unreliability, but to question the nature of narrative itself. Nabokov presents Humbert as a person who is ostensibly confessing to his deepest, darkest desires and is remonstrating having acted upon those desires. He mentally flagellates himself not only for desiring Lolita but for actually having sexual relations with her; by putting his mental obsession into physical form, he has betrayed both himself and her. However, because the entire story is told by Humbert, the reader has no way of knowing if any of it occurred. Humbert may be projecting his guilt over his unwholesome desires into an event that never happened. Humbert represents the falsity of all narrators and writers, including Nabokov; one irony is that he is apparently honest in admitting that writing, the “articulate art,” is only a “palliative,” a “treatment of my misery . . . .”

Humbert Humbert is one of the best examples in literature of an unreliable narrator. For example, Humbert Humbert lies to Charlotte and marries her in order to get close to Lolita. This decision alone reveals his disturbed personality and his skewed sense of morals, which quickly lead the reader to wonder how stable of a person Humbert is in general. Someone who lies and thinks very little of lying on this scale, while manipulating people's lives for his own gain, is not at all trustworthy, not in real life, and certainly not as a narrator.
As well, Humbert Humbert seeks out psychological treatment at sanatoriums, which seem to have little positive effect. Though Humbert Humbert might be using evidence of his poor mental health as a way to seek understanding and sympathy from the reader, his plan backfires, as the reader may find it difficult to believe everything this madman says about anything at all. At one point, he proves to the reader his instability when he explains that he has typed Lolita's name over and over on a page, which is strong evidence of his obsession with her to taking over his character.