All he had ever wanted was his father's attention.
Hours of his childhood could've gone by in his father's forge as he watched him work, happily chatting about nothing in particular, smiling when he smiled, and Celebrimbor wouldn't have noticed. It wasn't personal, but he'd always rather have spent the time with his father than his mother who, while nice enough, really just wasn't the same. There was something majestic about the glow of molten metal, something musical in the clang of hammers and hiss of steam, even if he flinched when the noise was too loud. And there was something about seeing the way his father focused so carefully on the details—that expression of concentration—that captivated him. He always wondered what was going on in his mind when he looked like that.
And sometimes, when Celebrimbor had done something particularly clever, he'd regard him with the same expression, too.
It was all his father seemed to care about anymore. All the work that he put in was always in pursuit of something petty; his oath, Nargothrond, a political marriage, even. It was disgusting.
But there was nothing Celebrimbor could say.
He couldn't look his father in the eyes and say that he wished they were back home, curled up on the couch while his mother hummed and made tea just in the kitchen, talking in tired-mumbling tones about all of the wonderful things that they had made, and all that they could make, given another day.
What would it be to simply tell him that none of that mattered? None of the riches and the ruin? To tell him that all he has ever wanted was his attention, that chasing power only hurt, that he couldn't see how that was more true to the oath than an afternoon well-spent. He couldn't.
His father wasn't there anymore.