The Diamond and the Duke — 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…