Elinor even advised her against it.

But "no, she would go down; she could bear it very well, and the bustle about her would be less." Elinor, pleased to have her governed for a moment by such a motive, though believing it hardly possible that she could sit out the dinner, said no more; and adjusting her dress for her as well as she could, while Marianne still remained on the bed, was ready to assist her into the dining room as soon as they were summoned to it.
When there, though looking most wretchedly, she ate more and was calmer than her sister had expected.

Had she tried to speak, or had she been conscious of half Mrs.Jennings's well-meant but ill-judged attentions to her, this calmness could not have been maintained; but not a syllable escaped her lips; and the abstraction of her thoughts preserved her in ignorance of every thing that was passing before her.
Elinor, who did justice to Mrs.Jennings's kindness, though its effusions were often distressing, and sometimes almost ridiculous, made her those acknowledgments, and returned her those civilities, which her sister could not make or return for herself.

Their good friend saw that Marianne was unhappy, and felt that every thing was due to her which might make her at all less so.

She treated her therefore, with all the indulgent fondness of a parent towards a favourite child on the last day of its holidays.