Their love is not one written about in stories.
There's no happy ending for them. It's not possible with the blood soaking the ground, with the anger and hate clogging the air between them.
It's debatable that what they have is even love. Regardless, the idea of living without it makes Madara burn.
He can't imagine going back to the way it was before. He loves how every clash brings with it the memory of roaming hands and softs promises burned into his skin with an equally soft mouth.
He loses himself in Tobirama's sharp red eyes, the only among all the Senju brave enough to meet his eyes. Not even Hashirama with his loud proclamations and naive overtures of peace (for an heir, not even a clan head, the boy presumes an awful lot).
The fights held between them really are like dances, for all Madara's half-joking calls for a dance. Tobirama moves like water. The smooth turns and twists of a stream, the destructive crashes of ocean waves, the swift coursing capable of gorging paths through solid stone.
Sometimes, Madara has no idea how they slot together so perfectly in all things. How Madara's fire doesn't burn and steam Tobirama's water.
How Tobirama's overwhelming, raging currents don't dampen and kill Madara's flames.
Peace seems unreachable, even in the dark of night when they let themselves truly live. Truly give in to their wants and desires. Even when they scrape out a moment of calm, where they just... sit, peace seems like a far fetched dream held by Hashirama and Hashirama alone. An impossibility.
Thank Kami Madara and Tobirama are known for doing the impossible.