Why did Diane Arbus commit suicide?

United States
March 2, 2009 10:48am CST
I'm was watching "Fur: An Imaginary Portrait of Diane Arbus" it's a great movie. I, also did a search on Diane Arbus on the internet, she was a well known photographer who photograph unusual images of her subjects. Does anyone know why she committed suicide in 1971?
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