Why are maya and Bailey hurt after their father takes them from the stamps

Feelings of abandonment by their parents encroach on Maya and Bailey's happiness; after their father comes and leaves, and they are sent back to Stamps from St. Louis, they feel like they have been abandoned for reasons that are their own fault. This leads to both of the children searching for the love of a mother figure and father figure, and varying degrees of success in soothing their feelings of being unwanted.