At least he was trying. He could have just written Merlin off and never even tried to build that trust again.

Arthur wasn't going to lie. The trust that had been there before he came here, before he knew the truth about Merlin's magic, it wasn't all there. It wasn't back yet. It was better than it had been in the beginning when he looked at Merlin and all he saw was a stranger.

"... perhaps, when you have the time, you can tell me the rest." Then he was pretty sure he could put it in the past, and move on.