"Right." Dean nudged the sandwich. "I know you haven't eaten since...the last time I saw you." He actually had to think about the last time other than the whole Fred situation he'd seen Jimmy. Cas was running away more often than not; he was...different. The City was changing the angel, and Sam.
"Balls?" The older Winchester looked a little confused. "What else was I was supposed to say? It'll get better? Just wait around until he goes home? His tour of duty is over as far as I know. Unless he wants to go to Jesse. And if he's looking for me to lead him, where the fuck am I going to lead him?"
Okay, so the hunter was getting a little angry. Cas just left this poor guy to fend for himself. Cas left his charge and was probably telling himself that it was exactly what Dean had told him to do. Just ran. Dean was also forgetting that he had suggested letting Jimmy live for a while.