As he is a man 'bewitched' I feel Darcy is really protecting himself rather than Lizzy. :)
He won't speak to her or even look at her.
She isn't even attempting to engage Darcy's attention.
My impression from the text is Darcy believed if not for Lizzy's inferiority; 'he should feel himself in some danger.'

I feel Darcy could've relaxed alittle; or gone out for a walk alone if he feels too near a woman aspiring to marry him. ;)