It happened inside the nail salon on Bergenline Avenue in West New York around 5:30 p.m. on Wednesday.
The exact relationship between the couple not immediately clear, she is believed to be his wife or girlfriend.
The couple has three children together and their 17-year-old son witnessed his mother being shot.
The victim, who worked at the salon, was pronounced dead at the scene.
The salon's manager was also pistol-whipped.
The suspect fled towards Kennedy Boulevard.
West NY police were on the scene in minutes.
Eventually they found the suspect dead of a self-inflicted gunshot wound at a nearby city owned parking lot.