Chesapeake Blue by Nora Roberts

Seth Quinn is finally home.
Its been a long journey. After a harrowing boyhood with his drug-addicted mother, hed been taken in by the Quinn family, growing up with three older brothers whod watched over him with love.
Now a grown man returning from Europe as a successful painter, Seth is settling down on Marylands Eastern Shore, surrounded once again by Cam, Ethan, and Phillip, their wives and children, all the blessed chaos of the extended Quinn clan. Finally, hes back in the little blue-and-white house where theres always a boat at the dock, a rocker on the porch, and a dog in the yard.
Still, a lot has changed in St. Christopher since hes been gone - and the most intriguing change of all is the presence of Dru Whitcomb Banks. A city girl who has opened a florist shop in this seaside town, she craves independence and the challenge of establishing herself without the influence of her wealthy connections. In Seth, she sees another kind of challenge - a challenge she cant resist.
But storms are brewing that are about to put their relationship to the test. Drus past has made her sensitive to deception - and slow to trust. And Seths past has made him a target of blackmail - as a secret hes kept hidden for years threatens to explode, destroying his new life and his new love...