What is the theme of Walk Two Moons by Sharon Creech?

The theme of Walk Two Moons is dealing with the loss of a loved one. In the novel, three characters lose their mothers in different ways. How they deal with that loss is dealt with by interweaving their stories into one.
Ben’s mother has been placed in a mental health clinic. He does not reveal the whereabouts of his mother to the other characters until near the end of the story. Some foreshadowing is evident when Ben objects to the term “lunatic,” which Phoebe uses for the young man who comes to the door.
Phoebe’s mother disappears, leaving home to deal with the arrival of the son she gave up for adoption before her marriage to Mr. Winterbottom (this is Phoebe’s “lunatic”). Phoebe refuses to believe her mother would willingly desert her family, so she comes up with a story that her mother was kidnapped. She believes that the “lunatic” is somehow connected to her mother’s disappearance, as indeed he is, but not in the way she thinks.
Sal’s mother has been killed in a bus accident. Mrs. Hiddle had left her family, meaning it to be only temporary as she went to visit a cousin after the death of her baby. Sal believes that if she can reach the place where her mother is resting by her mother’s birthday, somehow she can bring her home.
Each of these characters must come to terms with their loss, but also the pain of growing up, finding out that their mothers are fallible and even mortal. While Phoebe’s mother returns, having acknowledged her son to her family, both Sal and Ben must live with the fact that their mothers are not coming home. This seems to draw them together as they both come to terms with their loss but also their discovery of each other.