In his epilogue to "Pygmalion" (the play "My Fair Lady" was based on), George Bernard Shaw said something along the lines of: "A pretty woman of twenty has a very different attitude towards marriage than a plain one of twenty-nine." I like to think that Elizabeth would always refuse to marry purely for security (just as JA herself did) but if she found herself still single at twenty-seven, I think she would be a lot more sympathetic towards Charlotte's decision, even if that's not what she would do herself!