Her own idea of what is real is subjective to what she has witnessed thus far, which could be anything or nothing. She is entropic. The wife-not referred to as a woman or even given a name-is only referred to as an extension of the man.
We soon see that, after the man is called a booby by his wife, she begins to force her own subjectivity of nothingness upon him. The unicorn, which symbolized life and choice, then disappears and the man feels compelled to take a nap (symbolic of his acceptance of his wife's negativism). By choosing to sleep in the garden on his bed of roses (the symbolic center of life) the man expresses his desire to maintain a connection with life. It is this desire that later leads to the man's salvation.
The wife, however, continues to exert her own destructive influence by calling for the police and the psychiatrist in order to further deprive her husband of his freedom. But by choosing to utterly destroy her husband, who she is only an extension of, the wife is really destroying herself. This is proven when the police and the psychiatrist take away the wife in a straight jacket.
The man awakens, seeming to sense the presence of the police and the psychiatrist and, unlike his wife, is able to wake himself up on his own. The man is clearly a subject of his own reality. When asked whether he told his wife if he saw a unicorn, however, the man is forced to confront the center of his wife's destructiveness. By conceding to her what she previously desired (the negation of the unicorn and its existence) the husband is once again blessed with the vision of life, whereas his wife returns to the sleepy death from whence she came.