This of course made everybody laugh; and Elinor tried to laugh too. But the effort was painful. She was convinced that Margaret had fixed on a person, whose name she could not bear with composure to become a standing joke with Mrs. Jennings. Marianne felt for her most sincerely; but she did more harm than good to the cause, by turning very red, and saying in an angry manner to Margaret, -- (Ch. 12)

I think Elinor was hurt by Marianne’s warmth (Ch. 34) for a combination of reasons. Marianne just draws more attention to Elinor and prolongs the situation making it worse instead of better. It reminds me of Ch. 12 above. Also perhaps Elinor does not want Marianne to work herself into an emotional state (or more of one) on account of an offense meant for her which because of the source did not bother her greatly. One of my favorite elements in S&S is Elinor & Marianne’s relationship and the love they have for each other. Marianne although she has been often insensitive due to her sensibilities has shown on several occasion that she cares a great deal for Elinor and Elinor has been trying to guide and protect Marianne as best she can since Willoughby came on scene. (:D)