Queer as Folk, Season 5, Part 3 - Episode 13!
I still say that Justin would have eventually come back to Pittsburgh. Once Brian said he was fervently and passionately committed to marriage (and that he didn't return the rings) he would always be committed to Justin and that one day they would be together. In fact I have fanfiction's to illustrate that point at fanficition (dot) net - Happy Homo Heaven is one story.