Pieces of You — J.F. Elferdink

As Mark's body lies comatose, his spirit journeys to his past and then to two possible futures. Zachri, a supernatural guide, draws him into the changes in the lives of people affected by his decisions and alerts him to his potential to intervene. He must ultimately choose to remain with Janie, the woman he loves, or cross over and bring the forces of heaven to improve her world.