Similar to the friend zone which is usually female to male, except in this case the male 'girlfriend zones' the female. Even though the female would like to be just friends, the male cannot view her as anything besides a potential romantic partner. He will hit on her and then act upset when she doesn't want to be in a relationship with him. Victims of the girlfriend zone may sometimes be labeled as a tease.
This can go for both genders. (boyfriend zoned)
Ann: So are you hanging out with Ben after class today?
Leslie: No, he girlfriend zoned me hard. Hes a cool guy, but I can't hang out with him for more than 10 minutes without him making a pass at me.