You misunderstand me: I see the 'proofs' that Darcy uses to infer that she means to encourage him. I just do not understand why he misses the evidence on the opposite side of the question.

This is assuming (which I do, and apparently you do not) that Darcy was EXPECTING a 'yes.' Had he been unsure of his reception, then he may have seen all sides, and still been driven by overwhelming passion to propose anyway.

But if he had:

1) seen Elizabeth's 'arch' manner bestowed on Colonel Fitzwilliam (probably more than on himself),
2) noticed her allowing Darcy to attempt all the approaches to her, and never trying to engage him herself in return,
3) witnessed her withdrawal and discomfort caused by his references to her wanting to get away from Longbourne, to her staying at Rosings in future, and to his hints as to Charlotte marrying "well" (despite an unlikable husband),