It's not that Sasuke was hiding it, he simply had decided not to tell anyone. Those two things may be similar in nature and, in fact, may be the very same, but Sasuke refused to give it any more thought than he already had. Because, there was a distinct voice in the back of his head, telling him that he was running again.
What from wasn't difficult to determine: confrontation, explaining, potential heartbreak, and irreversible change. It didn't matter what would happen nor if anything would happen at all. Sasuke had long ago realized that people liked and cared for him more than they ought to, and this curse would result in hatred equally as often as it did in love. No, hatred was more common. He attracted that sort of attention in particular, like a beehive attracted bears. He too stung whoever touched him, but it seldom deterred people from trying and trying again to get under his skin.
In some cases, he was glad for it. He was glad that team 7 still extended a hand of friendship toward him, and similarly, he was glad that Taka had forgiven him for having been a horrible cunt and insensitive bastard. While Sasuke had gotten better with time, he was well aware that he could still be difficult to be around. And yet, he wasn't alone. In fact, he was less alone than he ever had been in his twenty years of life.
Karin had opened some doors while slamming others irreversibly closed. She was good at doing that, good at snapping him out of ridiculous fantasies of self-pity and regret, despite having her own demons to deal with. By now, Sasuke had learned that she had many of them, maybe even more than he. And every day they spent together, he thought he became a little better at navigating both his own darkness and hers. They fit together, and Sasuke hoped he helped her as much as she helped him. He hadn't known how much he needed someone like her.
And yet-and this was what had started his initial struggle-his friends (and hers) didn't quite know about them being a thing. It was a thing without a name, really, and it ought to have one, but Sasuke again found it easier to not have needless conversations when they fared well as they were. He figured he was her boyfriend, and that made her his girlfriend. It was odd though, to have such normal labels in their anything but normal lives. It created the illusion of being carefree and unburdened. Hearing it made Sasuke think of going on dates and buying gifts for each other. He wondered if she expected him to bring her a bouquet of roses and boxes filled with chocolate.
Though, well, he had bought chocolate the other day, if only because she had told him to. Maybe he could cross that off the list for now.
This "normal" of other couples, Sasuke didn't desire it. He didn't want to pretend they were something they weren't, and engage in activities that he doubted either of them would find all that much joy in. Maybe it would be exciting to pretend. Sasuke suspected that maybe Karin could like it for an evening or so, but he thought it might also sadden her. Her moods could change rapidly, and before he knew it, she would retreat into her own corner where she felt safe and comfortable, if only because it was familiar when the world around her was not. He'd need to join her first and then drag her out again. The short moment of being normal wouldn't justify what would follow. It wasn't worth it, so Sasuke chased the idea out of his head before it could fester.
He knew Karin sometimes wanted to feel normal. Sasuke didn't want that, but only because he had long since realized that there was no point pretending anymore. But, that didn't mean it didn't ache a little when Naruto had teased him about dating.
Somehow, that idiot had been able to tell that there was someone in Sasuke's life now. And, somehow, Naruto had managed to both congratulate him on finding this person and had made him feel bad for not acting like he ought to; for not having Karin on his arm and parading her around the village; for not going on a double date with Naruto and Hinata. And somehow, Naruto had managed to also bring Sakura into this, who "had known before even he did".
People were difficult. Sometimes, Sasuke pondered about whether it wouldn't be best to become a hermit and hide away in a cave for the next decade or so. Karin would probably yell at him if he proposed the idea to her, and Sasuke would have to concede that, yes, it wasn't sensible and, yes, it would be rather cold and wet in that cave. He would have to agree that, "Yes, Karin, I know I'm an idiot."
Despite his better judgment, Sasuke laughed. It was short, but it was weird enough to draw Suigetsu's attention, who was walking next to him.
"What's up with you?" he asked, and Sasuke shrugged.
He decided to humor him, "Something Karin said."
Or might have said, but Sasuke didn't feel the need to elaborate.
He watched from the corner of his eye how Suigetsu pulled a frown first, then stared at him with an evil glint in his eye. Sasuke had to hold back from smirking.
"You two seem awfully close as of late," Suigetsu remarked, putting his hands in his trouser pockets. "You sure you aren't ill? Might have caught something from her."
"We're dating," Sasuke said.
Suigetsu stopped walking. Sasuke continued on, now unable to stop himself from grinning.
He truly did love that girl. Maybe it was time to say it.