Enthusiasm by Polly Shulman (2006)

As the novel opens, Julie's friend Ashleigh, who is prone to obsessive enthusiams has just discovered Jane Austen, whom Julie has loved for years. In Ashleigh's attempts to recreate the Austen era, they crash a private school dance and meet a couple of boys. Much romantic confusion ensues, and a little Pride and Prejudice take-off—with full awareness by the young girls, who disagree over which of their potential beaus is Darcy. And which one Darcy likes. In addition to being charming and witty, with strong supporting characters, this is actually a sweet romance.