She couldn't believe him. No one could. It was frustratingly annoying, but there was nothing that Sam could do about it. He had screwed himself over and, deep down, he knew that there was a very good chance that he would never be able to get that trust back from any of them ever again. The concept sickened him on multiple levels; almost to the extent where he wanted to crawl into a hole and hide there for as long as it took for him to learn to accept the very fact.
He was doing his best to avoid looking much like a kicked puppy. Thus far, he was failing miserably. He'd been doing all right up until the literal slap to the face. Keeping himself neutral, making it easy for Faith to vent at him. He knew he had to get to that point again because he very well deserved it, but there was a bit of a struggle directed in his path. He'd need to overcome it.
"I started to make everything better," Sam explained quietly. "Do you know how much I've lost? Between my Mom, Jess, Dad, Dean - and that's just for starters. I couldn't stop any of it, and in a place like this, where everyone is together but always in danger? We needed it. Someone out there who could provide protection that doesn't consist of rock salt and bullets." He didn't move. Didn't know how to at the moment. "I never want to lose anyone again. Not my parents, not my brother, not Ben, not you. It's why I started. Then, somewhere down the line..." He looked down, feeling ashamed. "It got fuzzy."
Sam shook his head, shifting uncomfortably. "No. I don't think anything but the truth could have stopped me in this case, Faith."