why is this a significant episode in the novel ?

Elizabeth often meets Mr. Darcy while she's out walking.

She finds this an odd coincidence, especially since she had told him it was a favorite spot of hers, specifically so he'd avoid it.

Weird, right?

Darcy makes some comments that make her believe he is alluding to Fitzwilliam, and she wonders if Fitzwilliam is interested in her.

Elizabeth winces when Fitzwilliam comes to Charlotte's house one day and catches her alone.

Their discussion meanders from marriage to Miss Darcy. Elizabeth comments that, if she is like her older brother, she must like to get her own way.