"Elizabeth could not see Lady Catherine without recollecting that, had she chosen it, she might by this time have been presented to her as her future niece; nor could she think, without a smile, of what her ladyship's indignation would have been. "What would she have said? how would she have behaved?" were questions with which she amused herself. "

These are Lizzy's thoughts the day after the proposal, the day of her receipt of the letter. Do you think that these are the smallest beginnings of regret for her? I know that at this point, she does not love Mr. Darcy, but is she already beginning to think of what might have been? Or is she just having fun thinking of Lady's C's fury? I think I little of both, but that the seeds of regret for her refusal have been planted.