To become accustomed to something undesirable is to:

The term "inure" specifically refers to the process of becoming accustomed to something undesirable or unpleasant through exposure or habitual experience. When individuals are inured to a situation, they develop a form of resilience or tolerance toward it, allowing them to cope with the discomfort or pain more effectively. This concept can be applied in various contexts, such as dealing with adverse conditions, difficult circumstances, or unwanted experiences.

In contrast, the other terms present different meanings. "Inveigle" relates to enticing someone through clever talk or flattery, while "internecine" describes conflicts or struggles occurring within a group or organization, often leading to detrimental outcomes for all involved. "Irresolute" describes a state of uncertainty or hesitation, indicating a lack of firmness or determination. None of these alternatives convey the sense of adaptation to an undesirable situation that "inure" encapsulates.