Boundless by Lynne Connolly

She’s the unlikely wallflower of the extraordinary Shaw family. A woman who will never marry, but not for the reasons you might think . . .

Attacked on the streets of London, Lady Livia Shaw is relieved when a gentleman comes to her aid—and startled to discover her rescuer is Adrian, the Duke of Preston, a notorious rogue. But their association—and instant attraction—does not end there, much to the Shaws’ distress. For Livia was robbed of a memento—one that is both her most precious possession and a reminder of a shameful secret. It is a secret she knows will cause her to lose Adrian forever, yet he is determined to track down the thief . . .
Adrian never wanted to be anyone’s hero, but now he’s finding the prospect as pleasing as he does Livia’s company, and her beauty. Certainly he wants her in his bed, but what surprises him is how much she comes to mean to him. Which is why the revelation of her scandalous past is nearly his undoing. Arrogantly, he had assumed only he had the power to shock. But it is too late to turn back, and now Adrian may have to risk everything for Livia, even his heart . . .