Quote 7
These words, which conveyed to Elinor a direct avowal of his love for her sister, affected her very much. She was not immediately able to say anything, and even when her spirits were recovered, she debated for a short time on the answer it would be most proper to give. The real state of things between Willoughby and her sister was so little known to herself, that in endeavouring to explain it, she might be as liable to say too much as too little. (27.28)
The conundrum of communicating at all in this society is really quite shocking – there's always the danger of saying too much, or nothing at all. We're not sure how anyone ever got anything out in the open in Austen's day! Elinor can't even come out and say that she simply doesn't know.
Quote 8
Elinor drew near, but without saying a word; and seating herself on the bed, took her hand, kissed her affectionately several times, and then gave way to a burst of tears, which at first was scarcely less violent than Marianne's. The latter, though unable to speak, seemed to feel all the tenderness of this behaviour, and after some time thus spent in joint affliction, she put all the letters into Elinor's hands; and then covering her face with her handkerchief, almost screamed with agony. (29.7)
Interestingly, Elinor and Marianne seem to communicate most directly in a non-verbal fashion – we see them really commune for the first time in this scene.
Quote 9
Elinor placed all that was astonishing in this way of acting to his mother's account; and it was happy for her that he had a mother whose character was so imperfectly known to her, as to be the general excuse of everything strange on the part of her son. (19.2)
Family here serves as an excuse for inexplicable behavior – it's natural that the one thing that usually motivates weird actions here should be blamed even when there's no proof.