A Season of Flirtation by Julia Justiss
Lady Laura offers to take the shy banker's daughter under her wing. She doesn't have a title, but she has a lot of money. It's her first season and it's not going so well. She teaches her how to talk with the ton, how to flirt and how to get a husband.
There she meets her brother, a banker Miles Rochdale, who doesn't trust the ton and doesn't trust Laura with his sister. But there is something brewing between them, something that could never happen.
It's a lovely story, but I wished it more focused on romance.