Father’s Day by Debbie Macomber

Robin Masterson’s son, Jeff, thinks he needs a dog more than anything in the world. And there just happens to be one right next door! But the friendly black Lab belongs to Cole Camden, the unfriendliest man in the neighborhood.

Cole hasn’t always been so solitary, so aloof. The deaths of his wife and son have embittered him, something Robin can understand. Her own much-loved husband died when Jeff was just a baby.
Still, Jeff persists…and soon his mom and Cole are looking at each other in a whole new way.