Oh, there are so many examples! Just two, though?
Well, start with the beginning: their first meeting. When they meet at the dance, Darcy's pride makes him see the local women, including Elizabeth, as insufficiently attractive. At that same meeting, his proud manners make him seem distant and cold. This sets the couple at odds from the beginning.
Then, go to my favorite moment: when Darcy proposes. He explicitly states that he didn't want to love her, because of her family, and insults her pride—while she attacks his selfish pride for the way he's behaved. Pride shapes his proposal and her refusal.