Robin really had far too much fun at his expense. And too much time on his hands it seemed. "I knew who you were talking about because you are so predictable. And there is no one else you could be talking about. Except perhaps that girl who helped me find clothes. And yes it is Guinevere. I didn't realise you were so close to her that you used the shortened version of her name. And you're the one teasing me? I wonder what Thornton would have thought of this familiarity."
He should probably stop there. The more he attempted to defend himself, the more Robin would think he had reason to do so. And he certainly did not. Guinevere was very nice, but he certainly could not interfere. She was meant to be with King Arthur. Who was apparently not a King in this place.