A nagging girlfriend is typically one who is overly critical and demanding of her partner. She may constantly criticize his actions or choices, and try to control his behavior. This can be extremely frustrating and emotionally draining for the man involved. If you have a nagging girlfriend, it's important to try to communicate with her about your concerns. Explain how her behavior is affecting you, and see if there's anything she can do to change it. If the situation doesn't improve, you may need to consider ending the relationship.