...is that Bingley and Georgiana are not an item. Before seeing them together at Pemberley, Lizzy not only accepted Miss Bingley's claim that this was what the families wanted (even if she did not think Bingley concurred) but also felt that this desired match was one of the preeminent reasons for Darcy's interference in the Jane/Bingley connection.

That I was desirous of believing her indifferent is certain -- but I will venture to say that my investigations and decisions are not usually influenced by my hopes or fears. (from Darcy's Letter, Ch. 53)

In seeing Bingley, her thoughts naturally flew to her sister; and oh! how ardently did she long to know whether any of his were directed in a like manner. Sometimes she could fancy that he talked less than on former occasions, and once or twice pleased herself with the notion that, as he looked at her, he was trying to trace a resemblance. But, though this might be imaginary, she could not be deceived as to his behaviour to Miss Darcy, who had been set up as a rival to Jane. No look appeared on either side that spoke particular regard. Nothing occurred between them that could justify the hopes of his sister. (Ch. 44)

Finally, when Bingley and Darcy dine at Loungbourn, Lizzy can see that Bingley (regardless of Darcy's blessing) is still partial to Jane and that Darcy has not prevented him from returning to the neighborhood. At this point Lizzy can take some comfort in the thought that her own match with Darcy might aid her sister's happiness even more than Jane and Bingley's match might have led to a Lizzy/Darcy marriage. (After all, Lizzy still thinks Darcy's pride vis a vis a connection with Wickham more of an obstacle than Bingley's.)