Takes place during episode 212 and 214 of Shippuden.
When will this end? Itachi is dead, and Sasuke did not come home and did not seek forgiveness for abandoning the village. He delved further into darkness, with new vendettas and hatred that calcified his heart. Sakura saw what he turned that Uchiha fortress into. She knows of the corpses he has left behind. Will it end when the village, too, is rubble? How many comrades must fall to sate Sasuke's appetite for vengeance? The memory of who Sasuke was will no longer be disgraced by the criminal he has become. It will end today, with her kunai piercing his throat.
Sakura thinks of the kunoichi who lost their husbands to missions. Will she mourn as they do? Will her life change at all? She will still wake up every day alone, she will still practice medical ninjutsu, still stroll through the village by herself in the evenings, still go on missions, stand in Lady Tsunade's office for briefings. The only difference will be that while she does those things, she will be acutely aware of the fact that Sasuke is not simultaneously also waking alone and going about his life. When she thinks about it, though, she's done nothing but mourn since the day he left.
He doesn't sense her chakra as she approaches the bridge. He is standing over a woman, chidori channelled around his hand, as Sakura mouth opens to stop him before her brain has a chance to catch up. The person before her looks just like Sasuke. His voice carries the same timbre. His posture, the sway of his shoulders as he walks, the slight wrinkle in his brow, are all identical to the boy she remembers. But the person before her is not Sasuke. She doesn't recognize the man she loved at all. So when he says he wants to destroy the village, Sakura realizes the futility of revenge. Sasuke will never be satisfied. He will turn the world to ash if he isn't stopped, and standing in ash he will look for more things to destroy.
She had expected her stomach to drop when she saw his shape in the distance. It hadn't. She had expected her knees to go weak, her voice to crack as she spoke to him. She thought she would have to fight back hot and embarrassing tears as she asked to join him, but her voice remained steady and her eyes stayed dry. Maybe that's how he knew she was lying. Maybe he'd planned to kill her regardless as a way of hedging his bets. She spins around, realizing what Sasuke is about to do, her eyes going wide at the blue emanating from his hands before Kakashi's body is suddenly between them.
Sasuke looks like a madman, his eyes wide and darting around, ranting and raving about revenge. Kakashi tells her to take the woman at her feet away to heal her. He gives her a reassuring smile, and Sakura can't help but feel angry. Angry that she couldn't kill Sasuke, angry that Kakashi might die trying. Angry that every time she sees Sasuke, he tries to hurt her. The tears are coming freely now as she begins healing the woman. She repeats it in her head like a mantra: When will this end?