The Rogue’s Bride by Regina James

Having just emerged from mourning following her father’s death, Rebecca Harrington is exactly where she wishes to be: an unofficial companion to her aunt. Unfortunately, her ambitious uncle has other plans for her future. He lays down an ultimatum: either Rebecca marries the man of his choosing, or he’ll force her sixteen-year-old sister to do so instead.
To save herself from an unwanted marriage, Rebecca ventures into Robert Sterling, the Duke of Pembroke’s bedroom – and into his power. Now her reputation hangs by a thread and only a hurried marriage can rescue her.
Is the Duke of Pembroke the heartless libertine the world believes? Or will Rebecca discover unexpected honor in a man notorious for his wild ways? Will their encounter spark a passion that lasts a lifetime?