Look for Me by Moonlight

They call the big old inn Underhill, and it sits on the coast of Maine--an imposing sight. looming out of the desolate landscape. The locals say the place is haunted, and to sixteen-year-old Cynda, arriving to spend the long winter months with her father and his second wife, the stories just add to her feeling of isolation.
But when the mysterious, darkly handsome Vincent Mortanos arrives to stay at the inn, Cynda is mesmerized, His charm and sensitivity are irresistible; his attentiveness constant Cynda is sure she's in love. Daring to hope that the older stranger shares her feelings, Cynda is innocently blind to who he really is--or to the terrible danger of coming under his spell. . . 2001 ALA Popular Paperback for YAs