Fanworks play up his dramatic side and his insecurities, and honestly when it dominates what the actual game tells you, then people start taking it in as close to canon. I'm going to bet he'll start to crack a little in Hanamaru when he's injured, because yeah that's where the dramatic shit he says comes in. Being abandoned is a completely genuinely concern of his, but he's honestly over that time when Okita abandoning him and says as much. He's more mature than the fandom gives him credit for though.