Elizabeth certainly has trust issues. Which, I think, is based on her inability to truly forgive him for his initial slight. She claims all her friends understand why she wants to leave, but I think even Jane doesn't really understand. So much for being confidantes.

Darcy is understandably angry. They have agreed to be friends, & Elizabeth has encouraged the friendship, even stringing him along by flirting with him, when wham! she turns cold & unfriendly. And every attempt he makes to find out why, she rebuffs him.

In a sense, she just "threw him down the stairs".