Ever since leaving the job with the strippers and the siren, Sam had kept to himself. He still went along, acted like everything was good, but he just didn't want to participate in anything outside of that. He'd just go back to his room, watching TV or playing on the internet before going to bed in his own room, leaving Anna and Dean on their own.
No one wanted a third wheel. And obviously he was becoming that since Dean felt Sam wasn't good enough to be his brother anymore.
No, he wasn't good. He hadn't been since May, not like anyone but Ruby had noticed though. And as the months went by, Sam just felt himself slipping again. Losing that grasp of reality he had grabbed onto when Dean had walked back through his hotel door.
Slipping away, and he was so close to letting go and falling. And a part of him really didn't care if he did or not. Just as long as it was over and he could stop hurting inside.
He just wanted to stop hurting. Stop thinking. Stop feeling. Just kill Lilith and then it'll be over and the pain will go away.
So he withdrew further into himself, going between researching and finding jobs, or just numbing himself with the television. Like tonight, after coming back from the library, he just went into his room and stretched out on his bed, turning on the tv and flipping the channels to find something to watch for the hours it would be before he finally fell asleep.