In Pride and Prejudice, Jane Austen uses several instances to point out the class distinctions between Jane and Bingley and how it affected their relationship.
The first instance can be seen in the dialogue that takes place at Netherfield when Jane must remain because she is ill. After Elizabeth retires from dinner, Bingley's sisters make several comments criticizing Elizabeth's appearance after walking three hours in the mud and reproach her behavior. They even ask Darcy if he would ever want his sister doing such a thing (Ch. 8, Vol. 1). The implications are that they, as more genteel women than Elizabeth, and from London society, would never allow themselves to be seen in such a manner, especially just because her sister has a cold.
They then continue their conversation to disclose the working-class relatives of the Bennets. For instance, the Bennets have an uncle in Meryton who is an attorney, which is working class, and a second uncle who lives near Cheapside, London (Ch. 8, Vol. 1). Cheapside was primarily the market district beginning around the medieval period and still contains offices and outlets today. Since living near Cheapside would peg you as a merchant, we also know that the Bennet's second uncle is working class. As the Bingley sisters talk about the Bennet's relations, they make it very obvious that they think poorly of the connections. During this conversation, even Darcy says to Bingley that the Bennets' connections "must very materially lessen their chance of marrying men of any consideration in the world." This is a very pointed remark and Darcy is using it to remind Bingley that Jane is beneath him, and to advise him not to become too interested in her (Ch. 8, Vol. 1).