Pride and Prejudice questions the extremely high value that Austen's society placed on marriage as the only possible economic security for women who are not independently wealthy. By showing us the miserable marriage of the Bennets, and by grossing us out with the mercenary marriages of Charlotte and Lydia, the novel questions a system which places so much importance on this institution that it seems to endanger individual morality and happiness. On the other hand, with the marriages of Jane and Elizabeth front and center, the novel does allow room for good partnership as well.
Pride and Prejudice argues against the idea of "love at first sight."
Lydia's marriage is destined to be worse than Mrs. Bennet's.