Question

Why did Gilman most likely choose an unreliable narrator to tell tye story of "the yellow wallpaper"?

Answer 1

Gilman most likely chose an unreliable narrator to tell the story of "The Yellow Wallpaper" because it helps the reader understand that the narrator is not getting the help she needs. 
Thus she used the unreliable narrator to show us such feelings and emotions of helplessness. 

Answer 2

it helps the reader understand that the narrator is not getting the help she needs.