To be fond of dancing was a certain step towards falling in love

Bingley seems to be taking a quick step (pun intended) in that direction, or at least Mrs. Bennet believes so,

Everybody said how well she looked; and Mr. Bingley thought her quite beautiful, and danced with her twice. Only think of that my dear; he actually danced with her twice! and she was the only creature in the room that he asked a second time.

And Jane and Bingley are mutally attracted to one another.

"Oh! she is the most beautiful creature I ever beheld! "Bingley, Ch. 3

Jane, Ch 4: "He is just what a young man ought to be," said she, "sensible, good-humoured, lively; and I never saw such happy manners! -- so much ease, with such perfect good-breeding!"

Not only that, but Mr. Bingley's fondness for dancing puts him in good standing with the Meryton assembly.

Mr. Bingley had soon made himself acquainted with all the principal people in the room; he was lively and unreserved, danced every dance, was angry that the ball closed so early, and talked of giving one himself at Netherfield. Such amiable qualities must speak for themselves.

Darcy, who is not fond of dancing, finds no young lady to his liking and endears himself to no one at the Assembly.