Originally Posted by
JKtheMac
I just camt answer this question as a yes or no because too much is implied by the question.
The fact is there is no romance between them, AoU along with IM3 is frequently misunderstood, because people watching movies bring their own stories to the table and then critisise what they think they have watched.
In the case of this relationship it is being pitched as an emotional connection that is in the process of becoming more but is doomed to fail. It plays into each of the characters' wider story arcs, enhancing and teasing out their themes and motivations.
For Natasha it is a moment for her to struggle with the legacy of the Widow program. It is a means of explaining to the audience how F#%@ed up a system that takes children and turns them into assassins via psychological manipulation is. She is somebody that is ill-equipped for a relationship, not understanding how her manipulation of the Hulk transformation, and her compartmentalisation of "the monster" in each of them is holding back her emotional maturity and ability to relate.
For Bruce it only highlights how his personality is a divided 'Jekyll and Hyde' complex. He is confronted by a person who is attracted to him, who is broken and conflicted, but instead of seeking resolution and salvation in a relationship she is appealing to their symmetry. Bruce at once feels betrayed and horrified, he knows more than anybody the potential for destruction and horror, Hulk is. He is desperate for some kind of control and discipline, and yet the one person he has come to trust to help him, is not only prepared to use that part of him ruthlessly, but is equally emotionally il-equipped to deal with it.
So is this a romance? No, it is a story device. In a quiet moment of the movie it is teasing out the key emotional positions of each of the characters and pushing them towards their next story. For Bruce it precipitates his removing himself from the situation and possible future conflict, and for Natasha it sets her up for her internal conflict in Civil War.
As to the main controversy, that of sterilisation being the heart of Natasha's monstrous self image, I think this is again a misreading of the text. Unfortunately those individual ideas are butted against each other in her dialogue. But her speech is about the horrific ideology behind the Widow program as a whole and does not single out that one aspect. Natasha is trying to equate her overall experience to being a monster. That is a cry for help and not a statement about her as a monsterous character or specifically about sterilisation.