I would say this is the epitome of gun nuttiness. The guy harasses the woman and when she rejects him, he teaches her a lesson by shooting her in the back.
Is that sane?
No, it is not.
Was a gun involved?
Yes, it was.
This guy is the sort of person who should NOT have a gun.
In Japan, he would not have a gun.
In Denmark, he woulds not have a gun.
In Australia, he would not have a gun.