A/N: So this is super-short, but it kind of came out as a stream-of-consciousness thing that had its own natural endpoint. It's not what I originally intended it to be, but it's what I wanted to say.
He punishes himself on the salmon ladder because it's all he can do. He can't think, can't feel, can't allow himself to remember seeing her, seeing them, and realizing that it's all his own damn fault that he's lost her. He can't accept that he's destroyed the only good thing in his life, that she knew he loved her and walked away anyway. He knows he drove her away, but damn it, she was supposed to wait. She was supposed to let him find his way back to her, and accept him back with open arms and her own "I love you" and tell him he was an idiot but he was her idiot and she couldn't imagine a life without him so she just waited until he was the man who was worthy of her.
It didn't matter that she told him she wasn't going to wait, wasn't going to wither away and die in the basement with him while he threw their future and their happiness away with both hands. He heard her say the words but he never believed them, not until he saw her, saw them, and he had to face the reality that she had moved on, that every damn word she spoke was the truth and she meant it and he'd lost her. And he couldn't get her back. He couldn't say the words she needed to hear, couldn't be the man she needed him to be, and even if he could say the words and be the man, she'd already left him behind. She'd found someone who didn't hide his appreciation for her intelligence and wit and kindness and strength and beauty, and she allowed him in. She didn't turn him away and tell him that she was meant for someone else, even though she was.
So he threw things, and he had his temper tantrum, and he raged against the choices he'd made that had brought him to this place of misery and bone-deep regret. And when he was done throwing things he threw himself into a brutal physical assault on his own body meant to exhaust him until he collapsed. He pushes himself relentlessly, past the breaking point, past sanity, and all he can see is his own personal form of torture. The island, Fyers, Slade, none of them hold a candle to the sheer hell that is watching Felicity kiss Ray Palmer. The image is emblazoned in his brain and it plays in a revolving loop and he can't unsee it and he can't make it go away and he can't make it stop tormenting him and then she walks in, and he sees her, and his arms give out, and he falls. He's never fallen before.
She can break him like nothing else.
He expects her to rush to him, to make sure he's okay, because this is something she's never witnessed in their years together. Instead she watches him, and he picks himself up and stands, because he can't show her that she's destroyed him.
And then he really looks at her, and he sees in her eyes what he fears the most. She knows. She knows he saw her and Palmer, and she knows she's brought him to his knees. And by all appearances she doesn't have any intention of reversing course, she doesn't have any intention of telling Ray "thanks, but no thanks," and she doesn't have any intention of coming back to him. She understands that she's broken him, but he broke her first, and she isn't interested in putting him back together because she has to put herself back together instead.
Maybe not. Maybe she can't be broken; she's stronger than he is, even though she wouldn't ever think of herself that way. Maybe she just understood before he did that in order to keep him from breaking her, she had to leave him in the basement and seek the sunshine, on her own.
He sees that she's not unsympathetic to him; she's too kind and good to take pleasure in his unhappiness, and after all, they're still friends, still partners. They're just not… them, anymore. She's not his Felicity, and he's not her Oliver. She cares about him, but it comes with a limit, because it came at a price that was too high for her to pay.
And so he turns away from her, because the sympathy digs into him like a knife far sharper than the kiss, and he walks away. It's what he's good at. It's what got him here. And it's the only thing that can save him now that she's walking away, too.
A/N 2: Initially I was going to write from Oliver's POV, then have it take over from Felicity's POV when she walks into the Foundry, but again, my brain had its own ideas about where I was supposed to take this. I may still write a Felicity piece, starting from when Oliver walked away from her office after seeing her kiss Ray, and ending when he leaves her in the Foundry. I'm debating on that because I sort of feel like it would take away from the brutality of Oliver's emotional revelations in this one, but I would also like to flip it around and see her strength as a direct contrast to his breakdown. I don't know yet what I'll end up doing. Thoughts?