The Dreadful Duke by Grace Burrowes

He’d rather carry hod in hell…
Finn Cathcart, a successful sculptor, is having a fine time on the Continent cavorting with alabaster nymphs and marble goddesses (so to speak), when he’s informed that a ducal title awaits him back in England. The same family who disowned Finn’s father now needs an heir to prevent all their wealth from falling into the Crown’s greedy hands.

…She’d rather he did too.
Wilhelmina Cathcart is the widow of the previous ducal heir, and she has no patience with fledgling peers who come grumbling to their honors. Mina has a daughter to raise, meddling family to manage, and no time to explain Mayfair society to a stubborn, backward, contrary duke… even if he is charming and a good listener. Mina and Finn are on the point of admitting a powerful attraction when an enemy close at hand threatens to ruin their hopes for a happily ever after. They will have to work together, and put aside both well earned pride and treasured prejudices, if their shared dream is to bloom into a shared future.