6. She has a pet name for him.
You have been with your girlfriend for awhile and have been hanging out with your fellas even longer, but she can never remember any of their names—except for one. Not only does she know his full government name, as well as his mother's maiden name, she took it further, got a little too familiar, and created a nickname for him.
If it's just an abbreviation of his name, don't worry, maybe keeping it short helps her to remember. However, if she calls him "Superman", "Cutie", or "Adonis" – be concerned.