I remember my first domestic disturbance call like that.
I was trying to sort out what the relationships were between the parties. I asked the man who one woman was. "That's my wife," was the answer. I asked who the other woman was. "That's my girlfriend." Nobody blinked.
The disturbance occurred when the wife hit the girlfriend during an argument. The argument didn't have anything to do with the relationship between the parties... it was over her borrowing an article of clothing without asking.
