Possible interpretations. Our view
(1) The story is about a man who has hallucinations and tries to tell his wife about the things he sees. But his wife gets impatient and warns him to stop telling unreal stories or she will lock him up in a medical institution.
The man continues, so his wife desperately calls a medical institution.
However, when the doctors arrive they find the woman is very excited and the man very is quiet and coherent, so they think the crazy one is the woman and take her to the institution instead of her husband.
(2) This is the story of a man who plans to lock up his wife in a mental institution. So, he invents a lie to pretend he is nuts, and when his wife calls a doctor he denies everything and he makes the doctor and the policeman believe that the woman is crazy. Finally, they take her with them and his plan is a success.