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As for "lack of emotion" some are claiming. She is a medical ninja. Just like a real world doctor who is trained to put duty before emotion, she is putting what needs to be done first. It's not like Karin who is thrashing out erratically out of pure emotional trauma or Hinata who gets emotional and trips giving up. She is the strongest of the three. She'll be emotional when Naruto is alive and wakes up.
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It also helps that she had her meltdown in chapter 261, when she found out that extracting a bijuu kills the host.
She has had months to prepare for the possibility. She is keeping it under control right now, because it is necessary.