I enjoy watching the lady's face throughout, butt especially initial entrance, when the eyes and mouth start to open, and you can feel the head just get past the anal ring.
All three seem to go 'Oh!' at the same time.
Then as you begin to build a rhythm and she begins to move to drive you in deeper and begins moaning as she begins her pleasure trip.
Yes, domination, submission, trust and lust combining for a wonderful experience.
Naw, to tell you the truth, never saw the fascination.