Well, not to mention that it was basically the fanfic playing in Mackie's head while he was shooting a completely different movie, LOL!
So, really, Mackie was joking about his character being in love with Natasha, though I'm sure he's going to play it that way and ScarJo/Nat's going to be all, "What?"
I really do want to see the movie that Mackie was in in his own head, as well as the actual CA:TWS movie that we'll be getting. Mackie's version with prostitutes and coke and orgies w/ Black Widow sounds… decidedly not family-friendly.
From what we've read, it doesn't sound like Nat and Steve's getting romantic, so that just leaves Clint and Bucky… maybe. And those are canonical to Natasha, so. Yep. It really doesn't sound like there's a whole lot of room for romance in this movie anyway.