Oh, she says something like it in the novel, too:

[...] It was necessary to make [going into company more than she liked] a matter of pleasure, because on such occasions it is the etiquette; but no one was less likely than Mrs. Bennet to find comfort in staying at home at any period of her life. Ch. 18

I just do not believe we are supposed to believe her! She likes parties, gossip, visiting, hosting large dinners, socializing... She is a regular social butterfly!