Ben and Damon sat cross-legged on the ground at the center of Rita's office. It had taken a lot of pleading for his mother to let him do this. His parents knew the risks involved and wouldn't want to participate. But then, Nessa was at great risk and Damon would never live with himself knowing that there were chances of him helping Nessa and yet didn't take it.
The guilt would haunt him for the rest of his life so he rather die than not make a move at all. Moreover, he doesn't know who possessed Nessa. Damon was not ready to let go of Nessa with her in that state, but he was not ready to be with her either. He wanted the real Nessa, physically and spiritually.