P&P isn’t a romance novel, by our standards or back then either (it was and is a satire). The focus is on the social maladies even to the people who ascribe to them, that occur when one adheres to the social norms and how quite comical it can be when one chooses not to adhere to them, by just how silly and “romanticized” it can get.

That said, I don’t believe and didn’t read that passage as a “I’m not like other girls”, but more of “look how much he doesn’t think of me like the ones who approach him!” By now, Darcy has been SHOWN how judgmental he can be, and this scrutiny isn’t one based on sex (though we find that out later); but one based on pure character. Not even personality. If anything, he holds even his own little sister to this unspoken and private standard, one that is eventually shared with Elizabeth later in the novel. I believe one can fall for the setup of his pride, that Austen adopts. And read even into Elizabeth, our own sense of pride against Elizabeth’s prejudice.