There's this Steve/Tony fic where Tony proposes to Steve (I think) and they're all happily engaged I think this is halfway though the story.
Then Tony walks in one day: and tells Steve the wedding's off. Steve doesn't miss a beat and says no. Tony
Tony: The wedding's off
Steve (not missing a beat): No
Steve: Pepper/Rhodey said this would happen at least once. No.
Or something like that.
I'm sure it was part of a much larger story and it was on archiveofourown.
Thanks so much for your help :D