Charlotte is totally practical and down to earth. We look back at her statement about not wanting to know too much about her future husband with much the same shock that Elizabeth displayed, because our expectations (and Lizzy's) are different. Charlotte did not want to spend her middle years caring for elderly parents, and then tending to the needs of future nieces and nephews, so marriage was her goal. Charlotte saw the main chance and went for it, assuring her future regardless of what else happens. Everything else would be frosting.