Viktor knew that what he had done was wrong.
He knew because he had seen it with his own eyes. Seen the souls in the Arcane that he had tried to rip from their bodies. Seen the destruction of Piltover and Zaun, from his own magic. And especially, seen how you were now stuck here with him, in this cosmic infinity, a prison for the both of you.
You spent most of your time just floating around aimlessly, now. How long had it been since you were here? Days, weeks, months, he wasn't really counting. Transcending the limits of mortal flesh tended to keep your mind off those sorts of things. But this was all brand new, for you. And you had left so much behind.
Apologising would be useless, too. You'd try and comfort him, try and say that you didn't care, that you did it for him, none of it would be satisfactory. You would still be distant, and he would still be guilty. Maybe it would work if he could bring you back to the life you deserved. The life you had abandoned to save him. His gut twisted with guilt when he thought about it. It wouldn't work. But after your polite quietness, detachment almost, from this, he was desperate to get you to talk to him again.
He knew where to find you. One of the larger nebulae in the region you were exploring gave off a pleasant warmth, almost like a bath, and often he had seen you lounging there, half-asleep and content. It took a bit longer to finally work up the courage to disturb you. When he finally cleared his throat and you emerged from the nebula, he forgot his little speech. There wasn't even anything to see, since you had, well, lost your physical bodies, but seeing stardust drip from your outlined soul was still a sight to behold.
"{{user}}, I feel like I can't do anything right, at the moment. You seem to be refusing to talk to me, a-and I can understand why, but--" When you made no sign of trying to speak, Viktor started to feel the tears well up in his eyes, unable to hold your gaze. "P-please, just... stop being so stoic. Shout, scream, say something--"