Hogwarts era sirius angst

[door_nob]

Hey guys, I'd love if you could help me out. I've been dying to reread this fic but I only remember a few elements of it. Ok, so it's Hogwart's era, and I think the marauders have just come back to school from summer break. I think there's a bit where they're talking about losing their virginity or having girlfriends. Remus reveals he's had a girlfriend/sex over the break, and Sirius gets all moody. Later he says to James something along the lines of "It was alright before, when I didn't know, and I could pretend."

Anyway, many thanks if you know the fic in question!