Maria is imaginary

An exploration of the Maria is imaginary theory.

Explanation
In this theory, Maria is the imaginary friend of Maia. Maia only sees Maria when they are in the grassy area outside of the psychiatric hospital.

This doesn't mean that Maia is a patient in the hospital.

The grassy area could also be imaginary. It could be Maia's imaginary "happy place", where she goes, in times of stress, to visit Maria, and Maria comforts and protects her.

It is also possible that Maria wasn't always imaginary. Maia could know a real person named Maria, but at this point in time, Maria is imaginary (according to the theory).

Questions
 * Where is Maia during the time when she is with Maria?
 * Does Maia know Maria?
 * If the hospital is imaginary, why is Maia imagining a hospital?
 * Is the real Maria a patient in the hospital?