The Beginner's Goodbye by Anne Tyler
You'd think the quiet lives that Dorothy and Aaron led would end uneventfully. Then the storm came, which caused a tree to fall through their house, killing Dorothy. After Aaron moved in with his sister, Dorothy started coming back from the dead. As she shows up more and more, Aaron finds he's looking not only at their relationship, but his whole life. That includes the destroyed house, his disabled body, his bossy sister and a job in the family publishing business.