Warning: spoilers ahead for Avengers: Infinity War! Don't read any further if you do not want to know what happens in the latest MCU adventure!
It's no secret that Avengers: Infinity War is a crowded movie. The latest Marvel Cinematic Universe blockbuster is jam-packed with heroes and villains, and it thrives off of its ability to explore the subtle nuances of their relationships. One relationship that doesn't get too much attention is the romance between Black Widow (Scarlett Johansson) and Bruce Banner (Mark Ruffalo) that started in Avengers: Age of Ultron. Addressing this subplot during a recent appearance on the Happy Sad Confused podcast, director Joe Russo explained that the duo didn't have a more fleshed out reunion because much of their relationship is "unspoken." Russo explained:
There's a sort of unspoken truth that there's no need for a spoken resolution.
Remember, Banner and Black Widow do get a moment to reunite ahead of the Battle of Wakanda. They meet each other at the Avengers HQ in New York, and they share a knowing glance that implies that they're happy to see each other as more than just as teammates. Neither of them is particularly good at expressing his or her feelings, so according to Joe Russo's comments on the Happy Sad Confused podcast, they let that brief scene reveal the extent of their happiness to see one another. Years have passed since they have seen one another, and it wouldn't be within their characters to have a joyous reunion
The romance between Bruce Banner and Black Widow threw some fans off when it began in Avengers: Age of Ultron. Seemingly moving away from Liv Tyler's Betty Ross from The Incredible Hulk, the MCU put Hulk and Widow together because of their mutual sense that their pasts and life circumstances made them monsters. Marvel subtly nodded to the relationship in Captain America: Civil War and Thor: Ragnarok, so it's clear that the studio still acknowledges the romance, but it does not seem particularly interested in making that a front and center narrative element.
Of course, one other thing worth addressing about this is the fact that there's still one more movie to round out this story. Avengers: Infinity War may not bend over backward to tackle the love story between Bruce and Black Widow, but with Avengers 4 right around the corner, it is still entirely possible that we will see more elements of that love story. We already know that the fourth Avengers movie will round out an unofficial Hulk trilogy that began in Ragnarok, so it is easy to assume that Joe and Anthony Russo will make room for more scenes between Bruce Banner and Natasha Romanoff.