I appreciate it being pointed out that Catherine is shown as wanting to think the best of a friend at all times. She shows a bit of Jane Bennet in her with that. But I also find this part of the novel rather exasperating because, if you read a tone by the narrator of amusement, I am already getting to the point where I feel like saying to Catherine, haven't you seen through them already! 'Yes, she has befriended you in self-interest! She really is not interested in the Tilneys, or your feelings about them, and it's pretty easy to see.' Open your eyes a little more, Sweetie. (But alas, the novel is not going to change by my talking to it. ;-p )