During a party, after it has been established that Jane and Mr. Bingley are becoming an item, Charlotte suggests that it is prudent to let a man know your feelings rather than keep him guessing. It turns out that Charlotte's right—because Jane hides her feelings, Darcy is unable to see that she really does love Bingley.
Charlotte tells Elizabeth that it is best not to know anything about the character of your future husband. Happiness and successful marriages are always a result of happy surprise.
When Elizabeth rejects Mr. Collins, he turns to Charlotte, and she provides the sympathetic ear he needs.
Charlotte becomes engaged to Mr. Collins. When she explains her reasons to Elizabeth, she claims that she is not a romantic type. She knows she simply needs a secure marriage, and Mr. Collins is as good as she'll get at age 27.
Although she cannot approve of Charlotte's decision, when Elizabeth visits her friend at the parsonage, she admires the way that Charlotte has orchestrated her life so that she sees as little of Mr. Collins as possible.
Charlotte suspects that Darcy is in love with Elizabeth, but can't find any proof.
When Elizabeth and Mr. Darcy's engagement is announced, Mr. and Mrs. Collins come to Hartfordshire for a while to escape Lady Catherine's hysterics and temper tantrums. Charlotte is genuinely pleased at her friend's marriage.