Red Flag #1. You feel on-edge around this person, but you still want them to like you. You find yourself writing off most of their questionable behavior as accidental or insensitive, because you’re in constant competition with others for their attention and praise. They don't seem to care when you leave their side—they can just as easily move on to the next source of energy.
http://www.answers.com/Q/ Why the narcissist shares & amplifies his dislikes about you and your vulnerabilities with his new girlfriend. Great brief read further explaining how the new girlfriend is easily manipulated into the triangle and what keeps her so invested early during the relationship.