He concluded with representing to her the strength of that attachment which, in spite of all his endeavours, he had found impossible to conquer; and with expressing his hope that it would now be rewarded by her acceptance of his hand. As he said this, she could easily see that he had no doubt of a favourable answer. He spoke of apprehension and anxiety, but his countenance expressed real security. (Chapter 34)

Darcy’s confidence in her acceptance only exasperates Lizzy’s anger at him for dwelling on his scruples in proposing to her. Why is Darcy so confident? IMO Darcy feels encouraged by Lizzy although it is the furthest sentiment from her true intentions towards him. IMO this is partly due to Lizzy’s pleasant and entertaining manner which truly hides her real feelings from him such as noted in Chapter 10, even when she expects to affront him there is “a mixture of sweetness and archness in her manner which made it difficult for her to affront anybody…” Another reason is that Darcy is arrogant and believes he is a good catch no lady would turn down and it does not occur to him that Lizzy fails to recognize his attentions. In other words he expects encouragement and finds it. The conservation at the pianoforte at Rosings in Chapter 31 is a significant one because I think Darcy misinterprets it as encouragement from Lizzy:

"My fingers," said Elizabeth, "do not move over this instrument in the masterly manner which I see so many women's do. They have not the same force or rapidity, and do not produce the same expression. But then I have always supposed it to be my own fault -- because I would not take the trouble of practicing. It is not that I do not believe my fingers as capable as any other woman's of superior execution." (Chapter 31)

To excuse his bad behavior at the Meryton assembly, Darcy tells Lizzy that he is “unable to recommend himself to strangers” and the reason why according to Col Fitzwilliam, is “he will not give himself the trouble.” Lizzy, IMO, thinks this is a bogus excuse because Darcy is “a man of sense and education” who has “lived in the world” and with little effort should be able to recommend himself. Lizzy then compares his failure to trouble himself to her failure to practice the pianoforte pointing out that she is capable of superior execution if she made the effort hence he could do better if he made the effort—I think Lizzy means this to be a criticism but IMO Darcy does not take it that way due to her manner. IMO Darcy sees encouragement from Lizzy because she tells him personal information about herself; he may even think she is being very frank in admitting a fault to him. Also I think Darcy takes Lizzy’s comparison to mean she thinks they are alike. Lizzy’s failure to practice means she preferred other employments to perfecting her playing through practice in order to play perfectly for others—hence she does not perform to strangers. Darcy does not trouble himself to be introduced to, converse with, or be agreeable to people he believes are beneath him so also does not perform to strangers; therefore, he and Lizzy are alike in character so he thinks. I think the statement "We neither of use perform to strangers" is Darcy acknowledging their alikeness and compatibility with each other. ;D

"I do not mean to say that a woman may not be settled too near her family. The far and the near must be relative, and depend on many varying circumstances. Where there is fortune to make the expence of travelling unimportant, distance becomes no evil. But that is not the case here. Mr. and Mrs. Collins have a comfortable income, but not such a one as will allow of frequent journeys -- and I am persuaded my friend would not call herself near her family under less than half the present distance." (Chapter 32)

In Chapter 32 Darcy seems to be feeling Lizzy out on how she feels about leaving her family and living far from her home after marriage. Lizzy thinks he believes she is thinking of Jane and Netherfield and is embarrassed and her answer stays specifically on Charlotte. Her answer could be encouraging to Darcy because she indicates a lady could be settled too near her family but her look of surprise when he brings the question to her and Longbourn should have put a damper on it. I am not sure it did though.

More than once did Elizabeth, in her ramble within the Park, unexpectedly meet Mr. Darcy. She felt all the perverseness of the mischance that should bring him where no one else was brought, and, to prevent its ever happening again, took care to inform him at first that it was a favourite haunt of hers. How it could occur a second time, therefore, was very odd! Yet it did, and even a third. It seemed like wilful ill-nature, or a voluntary penance, for on these occasions it was not merely a few formal enquiries and an awkward pause and then away, but he actually thought it necessary to turn back and walk with her. He never said a great deal, nor did she give herself the trouble of talking or of listening much; (Chapter 33)

In Chapter 33 Lizzy recalls telling Darcy where her favorite walks are in Rosings Park so he can avoid them but of course he interprets this as her suggesting where they could walk together and purposely meets her there. While Lizzy may feel not paying attention to Darcy on these walks shows her displeasure I am never quite sure why she thinks that as being reserved as Darcy is, he does not find it disagreeable.

IMO Darcy does not act gentlemanly during the proposal and shows no concern for Lizzy’s feelings, it is basically all about him—his feelings, his scruples, why he is rejected with so little civility. Darcy is arrogant and full of himself but I do think he believed Lizzy would be receptive to his offer because he thought she had given him some encouragement—unfortunately, he is completely wrong. ;D