The story’s narrator is unreliable because of the events she describes in her secret journal. Her fixation with the yellow wallpaper makes the reader skeptical about her own mental health:
This paper looks to me as if it knew what a vicious influence it had!
There is a recurrent spot where the pattern lolls like a broken neck and two bulbous eyes stare at you upside down.
I get positively angry with the impertinence of it and the everlastingness. Up and down and sideways they crawl, and those absurd, unblinking eyes are everywhere. There is one place where two breadths didn't match, and the eyes go all up and down the line, one a little higher than the other.
I never saw so much expression in an inanimate thing before, and we all know how much expression they have!
In addition to her unnatural interest in the wallpaper, the narrator also seems unreliable as she describes impossible occurrences in her journal, such as how the pattern in the wallpaper seems to move and how she sees a woman creeping in the wallpaper:
The front pattern does move—and no wonder! The woman behind shakes it!
Sometimes I think there are a great many women behind, and sometimes only one, and she crawls around fast, and her crawling shakes it all over.
Then in the very bright spots she keeps still, and in the very shady spots she just takes hold of the bars and shakes them hard.
And she is all the time trying to climb through. But nobody could climb through that pattern—it strangles so; I think that is why it has so many heads.
The narrator also seems unreliable because she doesn’t seem to know her own mind. Her opinion about her husband constantly fluctuates. At times, she feels grateful for his care:
He is very careful and loving, and hardly lets me stir without special direction.
I have a schedule prescription for each hour in the day; he takes all care from me, and so I feel basely ungrateful not to value it more.
At other times, she is irritated by his constant watchfulness:
He asked me all sorts of questions, too, and pretended to be very loving and kind.
As if I couldn't see through him!
These examples from the text show how her judgment begins to become clouded by her fixation on the wallpaper. Her mind then applies this uncertainty to other aspects in her life, such as her husband. ~From plato