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to be unable to just watch (without doing anything); to be unable to look on in silence; to be unable to overlook; to be unable to remain indifferent to
見兼ねて、思わず口を出した。
Unable to just watch, I spoke up without thinking.
苦しむ彼女を見兼ねた彼は、すぐに助けた。
Unable to watch her struggle, he immediately helped her.
先生は、いじめを見兼ねるわけにはいかないと介入した。
The teacher intervened, feeling that she could not just stand by and watch the bullying.