The scene is this: Steve is talking to someone (almost certainly one of the exVengers) and insists that the whole 'war' was not about Bucky, it was about doing what's right, and that he'd do the same for anyone from his team. The other person gets pissed, and reminds Steve in detail about several instances when he utterly failed to 'be there for' various Avengers, and ends with a bitter: "So don't tell me you'd do the same for us, because you already didn't"
Not in the exact words, I think, but to this effect. Does anyone recognize that?
EDIT: found! Sine Qua Non part 2 of the Aftermath series by ficlicious -- http://archiveofourown.org/works/684115