Humans are such strange creatures. If something isn't witnessed firsthand, even if it's related to oneself, it doesn't matter—they'll eat and drink as usual, being an optimist through and through.
But if the event happens right before their eyes and they're involved, instinctively they'll start considering its connection to them.
Upon realizing that they might indeed be related to the event, and that a different approach could have led to a different outcome, they'll fall into a state of self-conflict.
Even if the action you took is separated by several variables from the final result, the feeling remains the same.
What's more, Su Qing, with the benefit of narration, is like a God with an omniscient perspective, able to predict the development of events, even their ultimate outcomes, intensifying his sense of responsibility.
'Blub blub blub'
