It's important to recall that the whole Bruce-Natasha chestnut is actually something the Russos inherited from Age of Ultron and, most specifically, director Joss Whedon. (They've said so themselves, calling the relationship between the two Avengers a "Whedon decision," though they've done their best to be diplomatic about it.) Everything about what transpired between the characters was, for better or worse, an extremely Joss Whedon thing to do: deconstructing a tough-as-nails woman to be vulnerable and weak before a man over something inherently linked to her gender identity — which, in this case, was Natasha's infertility. Whedon has insisted that Marvel demanded he cut the scenes that would have redeemed the relationship's apparent pointlessness and given it more heart, but frankly, nothing washes away the fact that Whedon made this explicit directive and it ended up in the final cut of Age of Ultron.
It would have been one thing if the relationship between Hulk and Black Widow had simply been a ham-fisted romance, but attaching that kind of sociopolitical baggage (and its resultant critical reaction) to it just makes the entire situation unpleasant to revisit. Approaching their relationship in any way is poisoned at the roots by this fact; Whedon opted to make the thesis, the commonality between them, entirely based on having Natasha equate them as monsters. What's more is that Natasha is presented a monster specifically because she was involuntarily sterilized as part of her training as an assassin — something she deeply she hates about herself. Bruce's monstrosity as the Hulk is also a thing he hates about himself, so it has always felt like the two were loving each other over the things they inherently loathed about themselves. What a great emotional bedrock to build on!
Still, you can't not address Bruce and Natasha's relationship before the end of the Infinity Saga if they're going to share screen time — and they do in the final cuts of both Infinity War and Endgame. In Infinity War, there was only one way to summarize the entire situation, and the Russos did it flawlessly through a single line of dialogue: Sam (Anthony Mackie) turns to Wanda (Elizabeth Olsen) and Vision (Paul Bettany) and mumbles "this is awkward" as Bruce and Natasha nervously confront each other for the first time in several years. That's it. It's uncomfortable for everybody — fictional characters, cast and crew, and audience alike. That's all anybody can do when it comes to Bruce and Natasha, and it's all anybody should do.
