Not really KuroTsuki but kinda is?? Really, it's just ~Angsty~
I'm sorry Tetsu (he's very lonely)
Despite the way he carried himself, and even though he seemed to be frequently surrounded by people, Kuroo Tetsurou was actually quite lonely. Perhaps it was because he and his friends were older and in their mid twenties now, and because many of his friends were in relationships, but he found himself drifting away from the people he'd once been so close with.

He'd always been a naturally affectionate person, one who thrived off spending time with friends, and it wasn't often that he spent time alone. Nowadays that seemed to be the case more and more often, and he wouldn't lie to himself that it hurt a lot to watch as his friends enjoyed themselves and their relationships while he was left behind.

Kuroo would and had, however, deny that he was lonely and hurting to any one of his friends if they asked.

He didn't want to be a bother to any of them when they were obviously happy and enjoying life without him around. Tetsurou had always put too much of his heart into friendships, giving and giving and never getting much back in return. Numerous hours being the support pillars for each of them as they struggled through heartbreak and stress and the hurt of life, yet never receiving that same support in return. Hell, he was the reason most of his friends had finally gotten together; Kuroo watched them all pine after each other for so long, watched them all fall in love and listened to them speak about their undying love. He only had himself to blame, he supposed, because now they were all in love and happy and had moved on from needing him.

It was selfish and wrong of him, Tetsurou knew that. He knew he should be happy for them, that he shouldn't be so jealous of their joy, but each time he spent hanging around Bokuto and Akaashi, or Kenma and Hinata, or Daichi and Sugawara, or Oikawa and Iwaizumi... he couldn't help but feel that way, and like he didn't belong anymore. Tetsurou wasn't a necessary part of their lives, they were flourishing and going further than they could without him bothering them.

These feelings had been growing and building for years now — since he was in highschool, and he was twenty five now — and there was no way he was going to break and spill them after so long. And so, as the months went by, he slowly began to distance himself from them. It was clear to him for a long time that they didn't need him around, but they were kind people; Tetsurou knew they wouldn't just toss him aside straight away, they wouldn't want to be that cruel. He knew they wouldn't tell him straight to his face that he was an annoyance, that whenever they hung out he just ruined it because they wouldn't be able to spend as much time together. Every time they asked him to hang out, he saw the way they looked at him, like they were silently pleading him to decline. Maybe it was his imagination, a result of the fear of abandonment, the eternal loneliness, the stress of work recently, or the lack of sleep, but even if that was the case and it was all in his head, there was no way he would risk burdening them with his pathetic issues.

Kuroo knew his mask was impeccable, that he could hide his emotions behind a smile better than anyone else. How else would he have known how to help everyone else who tried to hide how they felt when they struggled, but because he too was suffering? But his struggles weren't worth sharing and tainting his friends' happiness. If he would be the reason they stopped smiling, if him telling them his feelings meant that they were stressed and upset, Kuroo wouldn't forgive himself. It was better just to hide how he felt, like he had always done, because opening up would only bring them all pain and guilt and that was what he didn't want. The whole situation was one only he knew of, one only he was struggling with, which meant that Tetsurou was the issue, not Bokuto, not Kenma, not Akaashi.

There was only one reason he hadn't completely broken things off and left them to live their lives, and that was because he was still selfish. Tetsurou still wanted to see their happiness for a little longer, and so he resigned himself to pushing through from the sidelines until they were truly ready to move on without him. That was what he was doing now, lying on the floor in his living room and listening to the sound of the rain outside. He had things that he needed to do, but Kuroo lacked the energy to move from where he was. After so long of emotional exhaustion and pushing through, all the times he told himself 'I'm fine' and 'you're just being a baby', he had finally reached his limit. The world seemed bleak all the time, and even volleyball didn't bring him any joy anymore. Getting out of bed was a chore, not because he liked sleeping (since he rarely got enough sleep) but simply because it meant he had to start his day, and that was even more exhausting than wasting away the hours, waiting for a call.

He believed now it was finally almost time to make his move, to let them all go. That was what had been plaguing his mind all day, what Tetsurou had been thinking about as the world moved around him.

It was physically easy to take action, he knew it would be. It wasn't hard to change the locks on his apartment so the keys he'd given his friends years ago wouldn't fit. He could block their numbers, unfollow and block them on his social media, and resign himself to staying inside his apartment aside from heading to his job at the convenience store — the night shift, not that anyone asked — that none of them knew about. But Kuroo wasn't able to do that, as much as he was convinced it would be for the best if he wasn't around and ruining their lives.

Mentally, it was much harder for Tetsurou to process that he wouldn't get to see them anymore if he broke it off. Tetsurou had seen what love caused people to do, the lengths they would go to, and though it wasn't romantic feelings he experienced, he was no different. To him, it would be his final act of love for them, that he would leave them be for good, so that they could all be happy.

How long would it take them to even notice what he'd done? Would they care at all? He imagined their relieved faces, their laughter in celebration as they went on another group date, and that was enough to cause a sob to escape his lips.

There was only one person he still had left in his life now, though the issue of Tsukishima Kei and his feelings was another one entirely. The blond still lived in Miyagi, hours away, but that was exactly why Tetsurou hadn't broken things off with him. They talked on a daily basis, even only for a few minutes, and it was one of the only things that brought joy to Kuroo anymore. Kei didn't have to deal with how annoying he was in person, and Kuroo didn't have to try so hard to conceal how much he'd degraded. He actually found himself feeling genuinely happy during their conversations, without having to put on a mask, he just felt at ease. He could fool himself, that maybe there was some sort of hope for his future, someone out there that would stick around when everyone else didn't.

Kuroo was in love with the blond, and the prospect of a life with Kei by his side actually sounded nice. He imagined waking up next to him, making breakfast while the taller made them coffee, having someone actually see who he was and care for him despite his flaws. Yet, as much as he hoped and dreamed about it, Tetsurou knew that the chances of Tsukishima actually liking him back were extremely low, and he understood why completely. What was there to like, anyway?

The thought of that sent the tears flowing out uncontrollably, and the raven was helpless against his own emotions. When was the last time he'd eaten? He just wasn't hungry anymore; he never went out and he stayed still most of the day, meaning his body didn't need the same amount of energy as it usually did. A week had already passed since he'd seen any of his old friends, and Kuroo hadn't expected the complete lack of any social interaction to be so taxing on him. He thrived off people, he was affectionate, and even the little he'd had before was sustaining him. Now, he had nothing, and he was even more worn out.

If they had tried to call him — they hadn't, he checked his phone constantly for any sign that they did actually care — he was either passed out in bed, too exhausted to wake even from a banging on the door, or at work. He missed them all so much, Bokuto's cheerfulness and bright smile, Akaashi's gentle and caring nature, Kenma's attitude and strangely wonderful humour, Oikawa's alien theories and fashion advice, but there was no going back now. He left them, and even if there had been some sort of salvageable relationship before, he surely ruined it by what he'd done. Tetsurou knew it was for the better that he broke things off now; if he had to explain where he'd been, they would see how pathetic he really was, and then they definitely wouldn't want him because of that.

Even Tsukishima hadn't called or messaged as often in the last few days, and that presence, although digital, was sorely missed. By now, Tetsurou was certain there was nothing that could fill the coldness and the emptiness in his heart, because he truly believed nobody would want to waste their time with him.

His body ached from lying on the floor, his stomach stabbing and growling in its desperation for food, and the tears stung at his eyes. They always stung, but today it was so much worse. Physically he felt so many different variations of pain and suffering, but his heart was empty, and endless void of loneliness. He was longing to be loved, to have the warmth of care from at least one person, but that sort of life was a distant memory.

Kuroo Tetsurou heard his phone ring, and he didn't answer. They didn't need him, anyway.

(A/N - do you want a part two?)