User blog comment:Longlivemerlin/Merlin 'The Diamond of the Day Dialogue Teasers' UPDATE 3/@comment-204.12.159.225-20121220142912

“You know Merlin, all those jokes about you being a coward, I never really meant any of them…”
 * "I’m afraid I wont be coming with you – not this time.”

“I always thought you were the bravest man I ever met. Guess I was wrong”

This breaks my heart. I think that Merlin has to leave Arthur and be Emerys and just tells Arthur he's not coming. He doesn't have the time to be Merlin and then get away and be Emerys at  the same time. This also means that when Merlin is captured, no one is looking for him. This is so tragic.