In Derbyshire, Mr & Mrs G come to realise that Lizzy & Darcy's relationship, based on the time spent together in Hertfordshire and Kent, is deeper than the mere 'aquaintance' they had previously understood it to be. Darcy's attentiveness to their neice in Derbyshire speaks volumes, even during their very first, accidental, meeting at Pemberley. Then his successive compliments - introducing Lizzy to his sister, inviting Mr G (a tradesman, no less!) to fish in his rivers, and so on - all indicate a man very much in love, and trying his best to recommend himself in every possible way.

They take note of all this, and talk of it between themselves, adding 2 and 2 and coming up with the right conclusion as far as Darcy is concerned. But with no definite communication from Lizzy, they are constrained by social norms from mentioning it first. They are, therefore, confused about a) Lizzy's feelings for Darcy, and b) where matters actually stand.