An idiom meaning 'I couldn't die peacefully like this'—used to express extreme regret, resentment, or that one cannot accept a situation even in death.
大事な試合でミスをしてしまい、選手は死んでも死に切れない気持ちだった。
After making a mistake in the important match, the player felt he couldn't rest even if he died.
友人にひどく裏切られて、彼女は死んでも死に切れないほどの怒りを抱いた。
Betrayed badly by a friend, she felt a rage she couldn't put to rest even if she died.
家族にとって大切なものを失って、父は死んでも死に切れないと言った。
Having lost something important to the family, the father said he couldn't rest even if he died.