I think the second most beautiful thing about Furiosa and Jack (the first, of course, being the "My Jack", "My Fury" scene that still hits me like a throat punch) is that they didn't try to shoehorn in a typical romance. They didn't try to force today's version of what a relationship looks like onto these two because it would have never worked.
They took Furiosa, a girl who lost everything so early, that had only been the object of powerful men, who was forced over and over and over again to relearn everything she knew at the behest of monsters dressed as leaders, and gave her the Praetorian Jack, a man in a position of power that never took anything from her at all.
Dementus took her mother, took her home, and took her voice from her under the guise of affection. She was not a person, but an appendage forcefully attached to him.
Immortan Joe, for as kindly (very loose definition of kindly) as he treated his wives, saw her as nothing more than a womb, an object that he could use to birth a boy to continue his iron rule over the Citadel. He took her personhood, her childhood, just as surely as Dementus did. They both kept her in a gilded cage that she had no hope of escaping.
Then, she became a boy, and she was still only an appendage in the great war machine of Joe. She worked with the War Boys and the Black Thumbs as a replaceable piece of his engine that would someday lose its function or die.
And when she finally, finally, gets a chance to escape, to try (and most likely fail) to go back to a home that she can't even be sure exists anymore, she loses that, too. Except, this time, the man who comes back for her doesn't offer her a cage but a key. He sees in her a picture of himself, someone who has learned to be savage by force and not by choice.
He gives her a place to learn to be a person again, gives her the tools and resources to survive, gives her the limited autonomy that his position of power brings, and eventually even gives her his own past without taking anything from her at all. He gives her all of this and then was completely willing to let her go, never presuming that he would be allowed to go with her, only wanting to help her get wherever that was. And when she chooses him, chooses to trust him with the peach pit, he looks absolutely gutted, like he never thought in his wildest dreams that she would.
Their relationship is ambiguous when you look at them through the lens of modern relationships, but it is so beautiful in the context of the world that they find themselves forced into because it is a relationship that they chose. It doesn't matter if they never kissed, or never said "I love you", because it was never about that. It was about choosing each other over and over again, trusting each other with their squishiest places, and knowing for a fact that they would never hurt each other.
Praetorian Jack was a mentor, a peer, and the only person that Furiosa had ever been allowed to choose and he chose her right back.
