When I read "Evelina" by Fanny Burney (published in 1778- about the time we're looking at) a few months ago, there was a very interesting scene in which Evelina, young and naive, goes to her first ball in the big city.

A young man does ask her to dance but he is a fop and she declines him. He will not accept her refusal without some sort of reason. So she states out of self defense that she did not intend to dance at all.
A few minutes later, a handsome young man is properly introduced to Evelina by her chaperone. He asks to dance and she agrees. Off they go and it is her first dance in London. All happiness and joy!

But alas. Evelina made a terrible terrible faux pas. The fop learned about her dancing and in the end, he dueled with the man she did dance with.

Now this could just be Fanny Burney's rather fanatical sense of delicacy and manners in declining a gentleman or this could be a very real and common problem of a lady not wanting to dance with a gentleman but only being able to reject him unless she comes up with some sort of excuse that ruins her own pleasure in the bargain as well.

"That ladies to be considered perfectly free in regard to accepting or declining partners" seems to me a way for every young lady being able to accept or decline in however they see fit without being backed into a corner about it. Or harrassed.