Brian's monogamous and doesn't tell Justin who isn't

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So I'm being greedy and asking for more than one fic tonight... I'm bored, can you tell?

Anyway, are there any fics out there where Brian decides he wants to be monogamous  but doesn't tell Justin.  Then when he springs it on him and says "I'm clean and haven't been with anyone else in 6 month," Justin's like "well, you shoulda told me bc I HAVE been with other people"?  

I mean, it doesn't have to be anything close to that wording but something close to that general idea would make me happy.  I swear I've read something like this but it could totally be my imagination because I remember no other details.

EDIT: Some links in the comments but feel free to keep em coming!