A Queens man stabbed his girlfriend to death and then jumped off the roof of their seven-story apartment building as cops responded, police said Thursday.

When cops arrived at the building on Neilson St. near Dinsmore Ave. in Far Rockaway about 11:50 a.m. Wednesday, they found the 33-year-old stabber covered in blood standing on a ledge of the roof, a police source said.

Cops attempted to talk him down, but he jumped, plunging seven stories, the source said.

Medics rushed him in critical condition to Mount Sinai South Nassau. In addition to injuries from the fall, he had slash wounds on his wrists, ankles and torso, according to a police source.

Inside his apartment, cops found his 31-year-old girlfriend, Pheona Premraj, dead. She had been stabbed in the face, neck, chest and abdomen. The knife used to kill her was found next to her body.

Premraj’s father declined to comment Thursday.

A law enforcement source said the stabbing took place during a domestic assault. The couple shared the apartment.

A 64-year-old neighbor said the couple could often be heard arguing from inside their apartment.

“When they first moved in, they were good. But then three years ago, that’s when the fighting started,” said the neighbor, who asked that her name be withheld. “He asked her to leave almost three years ago. I heard him say, ‘You need to go,’ and she says, ‘No, I’m not going nowhere.'”

Cops confirmed that within the last three years they had been called by neighbors as many as six times to quell “family disputes” between the couple. No arrests were made during any of those visits to their home.

“The real bad part of the fighting started about a year ago,” the neighbor added. “The day of the incident, I didn’t hear anything.”