] I believe Henry and Eleanor, being such good people, have a genuine desire to be good influences to Catherine, regardless of wether Henry is looking for a wife or Eleanor for a friend. They see she has a good heart and has been brought up, as you said, "sweet" and "unaffected," and I might add, good-natured (but I won't say it more than once!!). But they also see that her relationship with the Thorpes is threatening to harm her sense of right.

Oh, I like this idea, and believe I can even think of additional evidence to bolster your argument. ;-)

I'm sure the Tilneys see right through the Thorpes, and can tell that they are shallow, selfish people. I think it a good thing that Henry met Catherine before she met the Thorpes, so Henry had a glimpse into her nature before she met the Thorpes.

When she drove past Henry and Eleanor in company with John Thorpe when she had promised to walk with them, I am sure Henry at least wondered if Catherine knowingly stood them up, was now so under the influence of the Thorpes that she behaved as they did. He was certainly cold to her at the theatre before she apologized. (and so sweetly - wasn't she adorable there? "I would ten times had rather been with you!")

Perhaps he and Eleanor did think they could be a good influence, or at least a different one for her than the Thorpes.