Most Helpful Guy
Because he is scared a guy will charm you into leaving him.2
Most Helpful Girl
Because he's insecure, or could be because he know how he thinks and doesn't want other guys to think pervertedly around you. All in all thats stupid0
But if they're just friends, you should let him know that it's okay. If you're going to let him stop you from interacting with other guys, that relationship is going to be 'suffocating'