A would-be ‘ass’-assin is in the wind after shooting his girlfriend in the rear end during a domestic dispute in Brooklyn, said law-enforcement authorities

The couple was butting heads inside an apartment on Kings Highway near East 98th Street in Brownsville around 6:30 a.m. Saturday when the 21-year-old woman tried to leave, police said.

As she headed for the door, her fuming boyfriend, 26, pulled out a gun and opened fire, shooting the woman in the rear, cops said.

First responders brought the victim to nearby Brookdale Hospital, where she’s now recovering.

Law-enforcement sources said she quickly identified her bum of a boyfriend as the attacker, but he fled the apartment by the time cops arrived.

The suspect, whom investigators have yet to identify by name, was still at large on Saturday.

A detailed physical description of the suspected shooter was not immediately available.

It remains unclear what sparked the initial argument.