In Ch. 24, when hearing on Charlotte's engagement to Mr. Collins, she tells Jane, "You shall not, for the sake of one individual, change the meaning of principle and integrity, nor endeavour to persuade yourself or me that selfishness is prudence, and insensibility of danger security for happiness."
Yet, she does just that in excusing Mr. Wickham for his very mercenary pursuit of Miss King. I have noticed that she makes a lot of excuses and allowances for Wickham.