In the fall of 1870, Crazy Horse invited Black Buffalo Woman to accompany him on a buffalo hunt in the Slim Buttes area of present-day northwestern South Dakota. She was the wife of No Water, who had a reputation for drinking too much. It was Lakota custom to allow a woman to divorce her husband at any time. She did so by moving in with relatives or with another man, or by placing the husband's belongings outside their lodge. Although some compensation might be required to smooth over hurt feelings, the rejected husband was expected to accept his wife's decision. No Water was away from camp when Crazy Horse and Black Buffalo Woman left for the buffalo hunt.  No Water tracked down Crazy Horse and Black Buffalo Woman in the Slim Buttes area. When he found them in a teepee, he called Crazy Horse's name from outside. When Crazy Horse answered, No Water stuck a pistol into the teepee and aimed for Crazy Horse. Touch the Clouds, Crazy Horse's first cousin and son of Lone Horn, was sitting in the teepee nearest the entry. He knocked the pistol upward as No Water fired, deflecting the bullet to Crazy Horse's upper jaw. No Water left, with Crazy Horse's relatives in hot pursuit. No Water ran his horse until it died and continued on foot until he reached the safety of his own village.  Several elders convinced Crazy Horse and No Water that no more blood should be shed. As compensation for the shooting, No Water gave Crazy Horse three horses. Because Crazy Horse was with a married man's wife, he was stripped of his title as Shirt Wearer (leader).

Answer this question "Why shouldn't Crazy Horse have invited Black Buffalo Woman on the hunt?" by extracting the answer from the text above.
She was the wife of No Water,