True. Then again, part of the blame still rests with Harry. Impatience and rash action was Harry's big weakness -- Snape correctly noted that he "lacked subtlety," and Harry got all peeved when occlumency didn't come to him immediately. He finally had to learn it for himself, by feel. Snape's own nastiness certainly didn't help matters, but Harry was partly to blame for it. For example, he never told anybody in a position to do something about it, about the way Snape was behaving. He simply gave up.
That was a frustration of mine throughout the book. It could have been renamed “Harry Potter and the Teenage Angst”. :)
And don’t forget he was sulking because Dumbledore was ignoring him.