] There's also that bit about how 35 is ancient, which must have delighted her 40 year old mother. And her railing about the impossibility of second attachments. Does she forget that she herself is the product of a second attachment? And her glee in abusing Col. Brandon et al with Willoughby, etc, etc...

Marianne has been annoying me for the whole course of the book so far, too.
It struck me especially that she is very intelligent and all the same she is so excessively besotted to Wickham. She agrees to everything he says and admires every single word he utters.
This sounds to me not like a clever and emotional young woman but like a brainwashed ninny. It's very difficult for me to combine these different images of Marianne.

Marianne's abilities were, in many respects, quite equal to Elinor's. She was sensible and clever; but eager in everything; her sorrows, her joys, could have no moderation. She was generous, amiable, interesting: she was everything but prudent.

(Chapter 1)

Elinor then heard Willoughby say in a low voice to Marianne, "There are some people who cannot bear a party of pleasure. Brandon is one of them. He was afraid of catching cold, I dare say, and invented this trick for getting out of it. I would lay fifty guineas the letter was of his own writing."
"I have no doubt of it," replied Marianne.

(Chapter 13)