The Portrait of a Lady as a Monster

Maybe Isabel Archer is shocked, shocked to realize finally - 500 pages into the novel! - that Osmond married her for her money and that Madame Merle arranged the marriage. Every reader will has seen this from the outset, and it's not just that "The Portrait of a Lady" is a novel with an omniscient narrator, it's not just that we see thing that Isabel cannot see and know things she cannot know. It's that Isabel suffers from a terrible character defect. Charitably, I'd like to say she's too trusting and sees only the good in others. But no I don't think it's that, I think she suffers from a perverse egoism. She doesn't see Osmond (or the phony Madame Merle) as good people, she's in fact drawn to their shallowness and cruelty. Why else would she turn down and turn away from two much nicer, kinder men and marry the worst one in the group? I don't think she misreads him at all. She sees that he's a snob and a good-for-nothing, the image of the nasty American, up in his Florentine villa complaining about everything, nobody's up to his standard, nobody's good enough - and Isabel likes this? Yes - she's cut of the same cloth. Her only desire is to be be independent, free - but free to do what? She doesn't have a thought in her head about making the world better, contributing to society, or even helping a single person. We know how little Isabel knows, but how little or how much does Henry James know? Does he know he's created a monstrous protagonist? Or does he see her as some kind of innocent ideal who has been ruined by the corruption of those around her?