Mr Bennet was not even present at some of these social events when he might have been expected to be - neglecting perhaps his duty as a chaperone to his daughters and leaving them to the less than socially polished direction of his wife. His absence from the first Meryton assembly suggests this as a possibility. If any the 4 dinners Jane had spent in Bingley's company were at Longbourne, he may well have escaped to his library, leaving Darcy and Bingley to an evening controlled largely by Mrs Bennet - hardly likely to impress Darcy on either score :) .