real reason shaw was killed?

Well, I can't watch videos at work, but in the Advent video we learn precisely why Shaw was killed...at least according to David.

She didn't reciprocate his feelings and tried to escape, David doesn't like things he 'loves' to leave him.

A simple, yet precise explanation... I wonder if it was causing her death that started his path down into madness... Making the mini shrine to her, and the grave stone, even though she was still clearly mutilated on his slab...