Merlin is, in relative terms, something of a god among men. He's the most powerful wizard ever to walk the Earth, loved by the people of Camelot and advisor to the most famous King the aforementioned people will ever have. Men, despite his oddly carved features, are desperate to be him, women tend to fall at his feet and, had he been more like Arthur was in his youth, they would have fallen with equal willingness into his bed.
But women, Merlin thinks, are also the cause of his suffering and, as he stares into the immortally beautiful face of the Lady Morgana, images of Nimueh, Morgause and Sophia flickering behind his eyelids, he wishes that, just once, he didn't always have to kill the really beautiful women.