"One other thing that has always bothered me, the idea of going out in an open carriage for a third time in such a short span of time was not proper anyway. James should not have been willing to compromise his sister's reputation like that nor Isabella's for that matter even if she didn't care."

I've been feeling rather sorry for James, because of his infatuation for Isabella. But your point that James should have realized that it was not proper for his sister to go out in an open carraige with Thorpe again in such a short span of time is very valid. It may be all right for James to go out with Isabella again since he intended to propsoe to her, and her manner to him gave him sufficient encouragement that he would be accepted -- they were a courting couple about to become engaged. But he should relize that it was not similarly proper for Catherine and Thorpe. He should have asked Thorpe to get one of the younger Thorpe sisters to accompany them instead. James' infatuation have certainly blinded him to the faults of the Thorpe brother and sister, and he had become completely deceived in them. I think James is in far more in need of a SUTH than Edmund Bertram in MP, at least Mary Crawford, unlike Isabella, is not insincere and did care for Edmund, and Henry Crawford, unlike Thorpe, is charming and well-mannered.