Buried Treasure (Wilder Hearts #4) by Laura Elise Bishop:
 
Cora Trevellyn is on a high from her first book tour when the woman who unknowingly slept with her husband turns up at her door. Leaving him, Cora flees London for Cornwall, to find solace in the town she grew up in. It’s not plain sailing though. The only man she has ever truly loved is there, and there’s stormy waters between them.

Jake Curnow is speechless when the red haired siren he has never stopped loving walks into his pub. Their relationship had always been secret, because of a mysterious centuries long feud between their families, but Cora is determined to find out what caused it, and she’s taking Jake along for the ride.

When their feelings for each other resurface, is their love for each other strong enough to withstand the storm ahead of them? Or will it sink like the treasure they’re seeking?