Captain America Drama: Hawkeye Reference by Black Widow in The Winter Soldier

Hawkeye did not appear in Captain America: The Winter Soldier. However he sure as hell was referenced by no other than Scarlett Johansson's character Black Widow. She wore a necklase which had an arrow on it. People would say this is stupid, that this is just a coincidence, but it is not. Joe and Anthony Russo- the two brothers and directors of Captain America: The Winter Soldier, have stated that this in fact is a reference to Hawkeye. Joe Russo has stated : "Honestly, [the arrow necklase], was a choice that Scarlett herself made as her character. Her relationship with Hawkeye will become very clear in Avengers 2". What does this mean? After all the hinting and sexual tension in Avengers is it possible that they are couple? I mean you could cut the tension between these two with a knife. The necklace does indeed hint towards a romance.