The Moonstone Marquess by Meara Platt

What happens when a battle-scarred hero bent on destroying himself meets an irresistible force by the name of Phoebe?

Lady Phoebe Killigrew is appalled by the scandalous country parties their new neighbor, a war hero marquess, is holding at his estate in Moonstone Landing. She has every intention of keeping well away from him, until a governess arrives at her door with his two nieces. They are mere children and cannot possibly reside under the same roof as that dissolute. When she storms over to demand he reform his ways or she will not give them over to him, she is unprepared for the feelings he stirs in her, for her heart understands his nieces are not the only ones in need of rescuing.
Cormac Stockwell, Marquess of Burness, has given everything for his country, including his left arm. He just wants to be left alone to destroy himself, but his beloved and meddlesome brother has unexpectedly sent Cormac his two little nieces, whom he adores, to care for over the summer. But how can he take them under his wing when he cannot even take care of himself? And now his impudent neighbor, Lady Phoebe, is pounding on his door and insisting he reform his wicked ways or she will not turn over the girls to him. He wants to tell the priggish, but beautiful, nuisance to mind her own business and stay out of his affairs. However, he must have been drunker than he realized when she came to his door, for he asks her to marry him instead.