This is a tough call, I think. I agree that the part about Georgianna ought to be kept very quiet.

But could Darcy have given some hints about Wickham's other past indiscretions? He might have quietly suggested to Colonel Forster that he'd known Wickham to have fled from gaming and other debts in the past. This kind of knowledge alone might have altered some people's opinion of him enough to make them distrustful of his goodness.

The funny thing about this circumstance, for me, is how Lizzy earlier blames herself in the same way, while in Darcy's presence.

"When my eyes were opened to his real character -- Oh! had I known what I ought, what I dared to do! But I knew not -- I was afraid of doing too much. Wretched, wretched, mistake!"