I've been wondering about that too. But then both Elizabet and Jane were witnessing some of the darker sides of marriage at home too and they still managed to develop a more sensible view of love.

My copy of P&P has an introduction by Tony Tanner. He contrasts Charlotte with Lydia (and the elder Bennets), arguing that one is an example of extreme prudence and the other of extreme imprudence. He claims that Elizabeth 'loves for the best reasons' - representing true balance between the two extremes.

It's an interesting interpretation - but I'm not sure Charlotte would agree.