I know I've mentioned this before, eons ago, but I think Mary would have known about the Charles - Anne proposal, it being such a small neighborhood (the only reason she didn't know about CW was that she was at school at the time). Plus, Louisa may have let it slip after one of Mary's rude days, don't you think (if not, she could have let it slip before going with H to Winthrop to give Mary something to think about besides their long walk!)? Mary deludes herself all the time--I'm sure she came up with some excuse for Charles for not asking her first, like he feared rejection and it would have hurt him so much more to have been rejected by her than by Anne...any nonsense that would show her in a good light! :)