'How could you help yourself from being married! [...] Was it my mother's project, then?'
'The Lord bless you, Arthur, and forgive me the wish!' cried Affery, speaking always in a low tone. 'If they hadn't been both of a mind in it, how could it ever have been? Jeremiah never courted me; t'ant likely that he would, after living in the house with me and ordering me about for as many years as he'd done. He said to me one day, he said, "Affery," he said, "now I am going to tell you something. What do you think of the name of Flintwinch?" "What do I think of it?" I says." Yes," he said, "because you're going to take it," he said. "Take it?" I says. "Jere-MI-ah?" Oh! he's a clever one! [...] Jeremiah then says to me, "As to banns, next Sunday being the third time of asking (for I've put 'em up a fortnight), is my reason for naming Monday. She'll speak to you about it herself, and now she'll find you prepared, Affery." That same day she spoke to me, and she said, "So, Affery, I understand that you and Jeremiah are going to be married. I am glad of it, and so are you, with reason. It is a very good thing for you, and very welcome under the circumstances to me. He is a sensible man, and a trustworthy man, and a persevering man, and a pious man. "What could I say when it had come to that? Why, if it had been--a smothering instead of a wedding,' Mrs. Flintwinch cast about in her mind with great pains for this form of expression, 'I couldn't have said a word upon it, against them two clever ones.' (1.3.90-98)
Affery is so terrified of Mrs. Clennam and Flintwinch that she cannot even imagine a way to avoid doing whatever they demand of her. Also, that's a fantastic bit about the wedding being just like a "smothering." Imagine being invited to something like that.