I had hoped to make a focus here about Mr Darcy's very special memory, I have not yet done it except by one example, sorry.
Mr Darcy has a lingering memory, and a memory that doesn't alter facts.
As it appeared rapidly that Elizabeth attracted him, and particularly when he examined the evolution of his opinion of her features, he necessary remembered where she was when she heard him, very precisely. I cannot imagine, reading his acts and the narration later, that he had the least impression that Elizabeth could have overheard his conversation with Mr Bingley. Even less, than he could have meant to be heard. I rather believe he was like Anne Elliot at the inn (Persuasion, last volume chapter 11 if I remember well) who, seeing that Capter Wentworth is closer from her than she had thought, is still... persuaded that he cannot overhear what she is telling to Captain Granville; meanwhile Captain Wentworth overhears and reacts fully, writing her a letter.