〜ないわけにはいかない

1. 1One is obliged to do something because of social relationships or a sense of duty toward others.Ex. 1
2. 2One must do something because the situation or common sense makes not doing it unreasonable.Ex. 2

Used when the speaker feels bound by social, moral, or situational reasons rather than a formal rule, often with a nuance of reluctance. It is common in both conversation and writing, especially in explanations of why one has to do something. Unlike the plain なければならない, it emphasizes that refusing or skipping the action is not realistically acceptable.

• わけにはいかないN3「わけにはいかない」covers a wider range: after the dictionary form it means "cannot do," the exact opposite of this pattern, while after the ない-form it is this very pattern, identical in meaning and usage.
• ざるを得ないN2「ざるを得ない」likewise means "having no choice but to do," and the two are interchangeable in most cases, though it sounds stiffer and more literary. It attaches to the ない-form minus 「ない」, with 「する」 becoming 「せざる」, and can also follow verbs like 「認める」 to mean "cannot help but admit."
• ないではすまない / ずにはすまないN1「ないではすまない／ずにはすまない」are close in meaning and often interchangeable, but they sound stiff and are mostly used in writing or formal situations, stressing that if you don't do it, the matter can't be settled and you won't be let off. They attach to the ない-form minus 「ない」, with 「する」 becoming 「せず」.
• なければいけない / なければならないN4「なければならない」and the like can express rule- or law-type obligation and can also attach to adjectives and nouns, whereas 「ないわけにはいかない」attaches only to verbs and stresses the helplessness of being swayed by propriety or circumstances. Avoid using it for rule-based or legal obligations.
• ないではおかない / ずにはおかないN1When 「ずにはおかない」expresses volition, it is an active, strong resolve to "absolutely must...," with a strong literary flavor and none of the sense of being forced. It can also take the causative form to mean "is bound to make someone...," a use that 「ないわけにはいかない」lacks.
• よりほかないN2「よりほかない」stresses that there is no other way and leans literary, attaching to the dictionary form or the ない-form, while 「ないわけにはいかない」focuses on propriety, one's position, or circumstances not allowing it to be left undone, and is neutral in register. Both express being compelled to do something, but with different emphases.

Unlike わけにはいかない after the affirmative form ('can't do'), this means 'must do'. ざるを得ない and よりほかない stress having no other choice, ないではすまない stresses that the matter won't be settled otherwise, なければならない is a neutral general obligation, and ないではおかない means something will definitely be done or will inevitably happen.