The Devil of Dashford Manor by Nadine Millard

Simon Taft, Earl of Dashford has spent years cultivating the reputation that earned him the name Devil of Dashford Manor. Having learned as a boy that women were to be admired, but not trusted, he is more than happy to revel in his bachelor life, and is determined to stay that way.
Amelia Linchfield is as studious as she is unobtrusive. Being a wallflower doesn’t bother her in the slightest, because she’s only in London to meet an illustrious archaeologist, and convince him to make her a part of his next expedition.
In a moment of madness, Simon decides to help Amelia get what she wants, even as he’s finding it harder and harder to fight his growing attraction to the willful wallflower.
They say opposites attract and never have two people been so opposite.
Can a bookish bluestocking really be the one to capture the heart of the Devil?