Verb (nai-form) + ではすまない

[Cannot get away without doing; must do]

Connection: Verb (nai-form) + ではすまない

Usage: Expresses that the situation will not be resolved or accepted unless the action is taken. Similar to ずにはすまない but slightly more colloquial. Implies social, moral, or situational obligation.

Comparison:

• ずにはすまない = slightly more literary
• ないではすまない = slightly more conversational but still formal
• Both express unavoidable obligation due to circumstances

Examples:

約束を破ったのだから、謝らないではすまない。(Since I broke my promise, I cannot get away without apologizing.)

これだけの損害を与えたら、賠償しないではすまないだろう。(Having caused this much damage, you won't get away without paying compensation.)

ミスを隠していたことが発覚したら、説明しないではすまない。(If it's discovered that I hid the mistake, I won't be able to avoid explaining.)