Aaron Hernandez -- Fiancée Called Cops After Bloody Mess at All-Night Party

Aaron Hernandez' fiancée called cops on him just a few months ago when he punched a window in their house, and bled all over the place ... TMZ has learned.

Sources tell us the incident went down at their rented home in Hermosa Beach, CA ... where Aaron and some buddies were partying from 4 PM to 9 AM.

We're told when Hernandez and Shayanna Jenkins began arguing -- because she wanted to pull the plug on the party -- Hernandez put his fist through a window.

His hand was cut badly enough that there "was blood everywhere."

We're told Jenkins called police in a last ditch effort to break up the party.

Law enforcement sources tell us cops have been to the house multiple times -- and that Hernandez "had no regard" for anyone who complained about his all-night parties.

The word neighbors keep using to describe him is ... "nightmare."