I'm only about 50 pages into the book so I'm not entirely qualified to post. I'd agree with those who say Lo is blameless, she's a kid with a childish crush on an older man. A man who takes advantage of the father figure shaped hole in her life.

The contrast between HH's beautiful writing and his despicable actions is breath taking. As to the original question in the op, I'd question why HH wanted his memoirs published posthumously. Imo he wants to clear his name, and believes his writing is seductive enough to do so. His continuous references to men who have taken child brides throughout history would support this. Also his manipulation of psychiatrists is a classic example of sociopathy (sociopaths appear to be immune to psychotherapy). Manipulation is second nature for sociopaths. I'd wonder if Nabokov knew of this and inserted it as a hint to HH's true nature.

I'm not sure how anyone could read it as a love story, unless it was as a forbidden/taboo love story. Lionel Trilling seemed to see it that way (there's an interesting discussion of the book between the two on youtube). But still!