I recently had something like this happen. My best friend of 18 years, [I'm 20 so I've known him my whole life] starting dating this crazy girl. She has changed him in such a way that he never talks to any of us, his 'former friends.' She told him she doesn't want him hanging around us anymore, we are bad influences. It upsets me that he actually listened to her. We go to the same school, and I saw him all of twice the last semester. He has become a recluse. All I hope is that one day he realizes he is alone because of this girl, who is quite unattractive by the way, and sees that one does need friends in life.