Happens all the time. [Keeping it vague, impersonal, on purpose. Because he doesn't like not having all his usual metaphorical armor in tact when he's out in public.]
People tell you you should trust more. So people try to trust. Open up. Get a world of hurt for it. [Hotch himself had brought Derek's trust issues into question on numerous occasions. And Derek was constantly working on it because of that. He even remembers telling Emily she should trust more and thinking how strange it was that he was the one telling her that. And now... all those walls he was working on tearing down inside of him were rebuilt and reinforced.
He shook his head.] Betrayal, dishonesty... it's human nature under the right circumstances. Shouldn't be all that surprising.