A Rogue of My Own by Johanna Lindsey

A Rogue of My Own - Lady Rebecca Marshall has been appointed as a maid of honor to Queen Victoria. Her roommate is a vindictive woman who attempts to embarrass Rebecca so she will have the room to herself. Rebecca also finds herself asked to spy for woman in charge of the maids. She gets entangled with Rupert St. John. St. John, who is a spy for the crown, believes Rebecca is spying for the opposition and seduces her into his bed. When she becomes with child, St. John marries her, until the lie of her pregnancy becomes obvious.