It's one the hardest scenes to watch cause you KNOW all Brian has to say is "Stay" and Justin would have but at the same time, it's not fair to Brian. He can't do that precisely for that reason because he BELIEVES Justin would leave him eventually.

It's just so screwed up and sad ad ugh...
Yeah, that's exactly it.
And maybe in that moment Brian WANTS to say 'stay', but forces himself not to, because the decision is Justin's to make.
Oh, our wonderful, fucked up boys. *sighs* *lol*