The Diamond and the Duke by Christi Caldwell

When a wounded soldier and self-proclaimed “beast” finds unlikely friendship with a headstrong and unconventional beauty, they quickly find themselves weaving a tale as old as time…
Despite a hero’s return to England from the Napoleonic Wars, Wesley Audley isolates from the ton. Deep wounds from the horrors of combat—and the despair of a broken heart—left him scarred. As he struggles to cope and resume his place in Polite Society, Wesley is quick to cut himself off from everyone…except for Ellie Balfour.
Independent and strong-willed, Ellie has dreams of captaining her own husband-free life and a penchant for meddling in other’s business. She knows befriending Wesley is a risk but Ellie can’t bear to see his heartache. Nor can she seem to silence all the temptingly intimate thoughts his nearness provokes.
But Ellie is yet to face a battle she can’t win—and Wesley’s heart is worth the fight. If only her campaigns ever went to plan…