Six Weeks with a Lord by Eve Pendle

Grace Alnott is out of time. To save her younger brother from an abusive guardian, her merchant father’s will demands she must marry a peer. Handsome but destitute Everett Hetherington, Earl of Westbury agrees to her offer of a marriage of convenience but stipulates she must live with him for six weeks. No matter how honorable he seems she can’t allow him to get too close, because the aristocracy cannot be trusted.

Six weeks. Major Everett Hetherington, new Earl of Westbury, has exactly six weeks to convince the very independent Grace Alnott to spend the rest of her life with him. Despite her belief she doesn’t belong in his world, he must tempt the alluring Grace into staying, because he has fallen for her. Hard. He just has to ensure she never discovers his secret.