It seems that Mrs. Bennet really doesn't care if Lizzy is happy with Mr. Collins or not. Despite Lizzy's refusal -- and Mrs. Bennet at least seems to know Lizzy well enough to realize that she really means it -- Mrs. Bennet tells her husband to insist that Lizzy marry him. On some level, it seems that even Mrs. Bennet knows that Mr. Collins isn't that great a catch -- she wants to keep Longbourn in the family and has decided, we are told, that the match is good enough for Lizzy, her least favorite child.