They had been doomed from the start. Zoro had known that. He'd known it from the very beginning that things between them would never really work. He'd assured himself of that over and over, convinced himself it wasn't worth the pain he'd feel later, told himself he'd only come to regret his feelings later. And after all of that, he'd still fallen in love with the shitty bastard.
Or maybe he'd always been in love with him. Sanji was fire, lighting up everyone and everything he came into contact with. He was impossible to miss, and once you caught sight of him, you couldn't look away. He was terrible beauty.
He came into Zoro's life guns blazing, almost literally. He had a bad temper and preferred to settle things with blows rather than words, and Zoro never turned down a fight. They'd been at each other's throats constantly. Their friends tried to keep them separated, like parents keeping their bickering children away from each other. But like magnets they found each other, butting heads and exchanging insults at every opportunity.
When had that changed? If Zoro could remember exactly when his feelings toward the blond had changed, he'd leap through time and fix it. He couldn't remember though, when exactly his feelings of irritation and hatred for the other man had changed into respect and admiration. He couldn't remember when he started looking forward to their arguments, and hoping they'd be able to fight. He couldn't remember when he looked into Sanji's eyes and noticed the same emotions there, reflecting back at him. The same interest, the same joy in fighting with Zoro as Zoro felt fighting with Sanji.
It was right about then, when he noticed Sanji looking at him the same way, that Zoro started telling himself to quit while he was ahead. Sanji was a known ladies' man. He took a different girl home at least three days a week, and had a little black book full of flings and one night stands. It was no secret; Sanji was promiscuous.
Zoro had never had those kinds of desires. For men or women, that wasn't Zoro's cup of tea. He filled his life with close relationships, desiring only close emotional contact, but never physical contact. He surrounded himself with friends he could count as close as family, and while that had always been enough for him, he found life a little lonely sometimes.
Sanji filled that loneliness. Every moment with Sanji filled the cracks in Zoro's existence. Sanji was the only one Zoro needed to see him, the only one he felt a deep need to spend time with. He opened up to Sanji, let him into his life in the most intimate ways Zoro knew how.
He was shocked and surprised when Sanji did the same. Sanji, the ladies' man, opened up for Zoro. He stopped seeking out his nightly flings; he tossed out his book of addresses. He only had eyes for Zoro, and Zoro couldn't have been happier.
They grew closer, Sanji was everything Zoro had ever needed. It would always go down in his memories as one of the happiest times of his life. Zoro would never forget the feeling of completeness he felt with Sanji. He would never forget the nights spent lying awake, wrapped in each other's arms, relishing in the existence of one another. He'd never forget the joy he felt in waking up to breakfast with Sanji. He'd never forget their late night discussions, their movie nights, their few but exciting dates. He'd never forget their sparring sessions, where their bodies would meet with jarring force, and their souls would resonate on the same frequency.
But as happy and full as Zoro's life had become, it was obvious Sanji's was draining through the cracks. Every advance Sanji made was ignored, misinterpreted, or rejected. Every suggestive whisper, every encouragement for more touching, every straying hand was rejected by Zoro. He couldn't do it. Even with Sanji, the man he loved so much, Zoro couldn't muster those kinds of desires.
It was painful for Sanji.
Zoro could see the hurt he was causing. With every refusal to cooperate the way Sanji wanted him to, he could see the pain of rejection, the loss of confidence, and the frustration he was inflicting on his dearest person. He tried, God, he tried so hard to show Sanji in other ways just how much the man meant to him. He tried to show Sanji just how much Zoro loved him, and how much he needed him.
But it wasn't enough. It wasn't enough to keep Sanji from seeking out his own desires elsewhere. It wasn't enough to keep Sanji from being entirely absent some nights. It wasn't enough to keep Sanji to himself.
Zoro knew. He wasn't as stupid as Sanji liked to call him. He knew what was happening, but he couldn't bring himself to acknowledge it. If he did, he'd lose everything again. It was selfish, but he couldn't.
Sanji ended things between them some time later. By that point, things had been over for a long time already. The words Sanji spoke on that day only solidified it for the both of them. Sanji knew Zoro wouldn't have let go without those words. He knew. Because he knew Zoro better than anyone.
They had been doomed from the start, Zoro had tried to warn himself. He wasn't normal. He knew that. He was different. He'd never thought to question it before, he'd never thought of it as a curse. Now as he watched Sanji flirt with a voluptuous beauty at the bar, however, he felt differently. It was a curse, and he'd never be complete again.