This happened on Lazywood Lane and Wayside shortly before 11:25 p.m. Monday night in southeast Houston.
Police say 31-year-old Maria Martinez and her husband were driving when they got into an argument.
That's when Martinez allegedly stabbed the 26-year-old man in the chest.
He was taken to Memorial Hermann Hospital where he died.
At the time of the stabbing, officials said Martinez claimed self-defense.
The victim's identity has not been released pending the notification of his death to his family.