One of my favorite parts of that allegory (and I paraphrase) is "men have the freedom of choice and women only the power of refusal." In a dramatization I saw about 10 years ago on PBS, Catherine responded with "Do not underestimate the power of refusal." I thought that was a brilliant line, but the book's Catherine cannot speak well enough to be either unintelligible or that sharp. She is not aware of the power she does wield; if Thorpe knew what she thought of him, it would be quite a blow to him, and as you say, just spending time with Thorpe has piqued Tilney's jealousy.