We could never relate to a perfect Henry. So JA has made him wonderful but with human flaws. He is not perfect nor is he right 100% of the time.

When Catherine first meets the Captain, she observes that his manners and taste are inferior to his brother's. And as much as she loves Captain Tilney's brother, she eventually admits that she can not like Captain Tilney himself. She is able to come to the conclusion that he made believe he cared for Isabella for mischief's sake and Henry agrees with her.

Catherine is able to admit that Isabella was wrong and see her true character but Henry can not admit that his brother was wrong. When Catherine is pleading with Henry to do something about Captain Tilney's flirtation with Isabella and to inform him of Isabella's engagement to James, Henry says that his brother is aware that Isabella is an engaged woman.

The Captain is way out of line and guilty of behavior unbecoming of a gentleman. His disrespect of James is unpardonable, a major offense in which he might have found himself facing a duel a decade or so earlier, though with someone more temperamental than James I would imagine.

Henry and Catherine engage in at least two conversations about the Captain's behavior. This is one subject in which Henry drops the ball in my opinion. In the first conversation, when Catherine expresses her disapproval and is concerned for her brother, Henry's general attitude (and I'm going by general memory, here so I hope I've got it right) is Frederick knows what he's doing, I've done as much as I can do anyway by informing him of Isabella's status, nothing ill is likely to happen, and everything is bound to turn out okay for all three. Catherine remains uncomfortable but defers to Henry's judgement but she was right to have been worried. In the second conversation, after the fact/Isabella's letter, and Catherine is trying to figure out the meaning/purpose behind Captain Tilney's behavior in the whole matter, she ends up allowing herself to be humored and complimented out of her bitterness toward Frederick. Catherine was tenacious in both sets of conversations and if I remember correctly, Henry in his effort to release himself from what is obviously and uncomfortable position concerning his brother, turns on the 'Henry-charm'.

Catherine sees that Isabella's flirtatious behavior did not justify the Captain's. They were both wrong. Henry is laying the blame at Isabella's feet. This is just one of those times, IMO, when the reader has to admit that Henry is not perfect.

Very rambling, should have been in bed half an hour ago. :)