"The Snow Ball" by A.R. Gurney

This 1980s period novel set in Buffalo, NY, includes 50s era cotillion scenes and a nostalgic revival of the winning dance by the talent of the day.
Quotes include the protagonist's mother telling him he was sent to dancing school when he was ten because, "that made you old enough to behave and young enough not to refuse."
Many scenes of a bad dance classes culminate in Jack, the talented young man from the other side of the tracks, leading Kitty, the pretty rich girl, well enough that they considered going pro.
I liked one metaphor. "Cooper knew from experience what it was like for a man and a woman to move well together on a common enterprise. The sounds and rhythms of his old domestic dance with Liz still echoed through their now empty house, through their present life."