What does the 2nd message mean on porch in walk two moons?

The second message on the porch in Walk Two Moons is "You are not in any trouble." This is a message from Phoebe's mother, who has left her family and is now living in a mental institution. Phoebe's mother is trying to reassure her daughter that she is not responsible for her mother's illness, and that she should not feel guilty about it.