Mrs. Bennet is an annoying type of character. Elizabeth "cringes" and "blushes" for her mother (Austen 67). Even with this particular nagging quality, she is still, in a sense, a good mother. She is the way she is because of her desire to see all of her daughters wed and well-provided for. Mrs. Bennet feels on top of the world when Jane hits it off with Mr. Bingley. And upon hearing that Elizabeth will not accept Mr. Collins's marriage proposal, she claims that she "will never see her [Elizabeth] again (97)." Wanting Eliza to accept the offer was of a selfish reason, of course, however, it could have very well been also her insecurity of thinking that Eliza will never find someone to marry in the near future. I think deep, deep, deep, deep down, there was slight good intentions of wanting Elizabeth to just be taken care of.
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Austen, Jane. Pride and Prejudice. New York: Bantam Dell, 2003.