Mapping interpersonal-to-cognitive pathways with suicidal ideation: unforgiveness-based moderators within the interpersonal theory of suicide framework

Background: Suicidal ideation among young adults is a significant public health concern. While the Interpersonal Theory of Suicide (ITS) provides a robust framework, the role of unforgiveness-based coping responses to interpersonal transgressions remains under-specified. Specifically, how strategies like avoidance, self-dysfunction, and revenge relate to the strength of ITS associations requires clarification. We examined cross-sectional associations among thwarted belongingness (TB), perceived burdensomeness (PB), hopelessness (HL), and suicidal ideation (SI), and whether these associations varied by unforgiveness-related coping (avoidance, self-dysfunction, revenge) within a moderated serial mediation framework. Methods: Standardized questionnaires were completed by 205 university-affiliated participants in Hong Kong. Given the cross-sectional design and zero-inflated outcome data, SI was modeled with Bayesian hurdle lognormal regression. Competing structural specifications were compared using WAIC/LOOIC to evaluate model plausibility. Results: Model comparisons favored a serial specification over a common-cause model. PB was robustly associated with both the presence and severity of SI. Moderator analyses indicated that avoidance and self-dysfunction were associated with a stronger link between TB and PB. Revenge motivation showed a complex pattern: it was associated with heightened hopelessness but reduced likelihood of reporting SI. In this non-clinical university sample, this pattern may reflect a form of emotional externalization, temporarily deflecting internalizing distress outward rather than conferring stable protection; this interpretation remains conditional on the cross-sectional design and sample characteristics. Discussion: Unforgiveness-based coping strategies appear to be associated with distinct points in the interpersonal-to-cognitive sequence. The "deflection" effect observed with revenge motivation should be interpreted with caution, likely representing an unstable externalization response rather than adaptive protection. Conversely, avoidance and self-dysfunction are linked to entrenched interpersonal distress. Integrating unforgiveness-based coping into suicide risk assessment offers a more granular understanding of risk. These findings highlight the value of assessing coping styles in youth-serving settings, suggesting that brief screening and low-intensity supports targeting specific coping mechanisms may be valuable for suicide prevention.