]her snotty set-down of the "agéd" Colonel's matrimonial prospects is the first instance where I become positively exasperated with her. Her tone here is so absolutely condescending; she makes it so clear that she considers that notion of a match between herself and Brandon as insulting and ridiculous beyond description

What irks me about this is not that Marianne can't see Brandon as a potential husband for herself (I don't think it out of the ordinary, even back then, for a 17 year old to find a 35 year old man too old for her), but that she doesn't think he would be husband material for anyone, and that any woman who married him would just be playing nursemaid to him all the time.