It's impenetrable. He's caught a glimpse of the warmth, and the joy and the sorrows of it, and knows that if he can just get in, it'll be like home. But it's not a thing he can become a part of just by wanting. It's so hard to earn that kind of trust. Almost impossible. And even if he was lucky enough to be allowed a foot inside, he could never allow himself to take it for granted. A misstep, and the door can shut like a bear trap. Steel strong and cold. Shutting him out.
Even then, it's not like he would ever really belong. You have to be born into some things, he knows. And he can see it in their eyes. They can't help it. They want him to belong, but no matter what, he will always be on the outside.
And for all they've got the whole world bearing down on them like a semi in the night, Bobby thinks to himself, the way those boys have each other— Well, he'd hate to be the world right now.