Oooh interesting! They seem like a couple in the group when Ultron first appears (I love what Nat's wearing btw)

Given the previous films it does seem a bit out of left field to possibly develop a romance between them but if so, hopefully it won't be forced or shoehorned in for the sake of it.

That's one advantage of being a slash shipper though, I can just continue to ignore the canon romances quite merrily (having said that I ship Steve with just about everyone). :D