Relationship learning and relational trust as complementary and substitutable mechanisms: evidence from Vietnamese organizations

Purpose This study aims to examine how relationship learning and relational trust jointly shape relationship performance in Vietnamese organisations and distinguish this model from relational governance studies that treat trust and learning mainly as separate antecedents. Design/methodology/approach Survey data from 565 employees and frontline or middle managers were analysed using a parsimonious partial least squares structural equation modeling (PLS-SEM) model comprising relationship learning, relational trust, relationship performance and the learning × trust interaction. Measurement and structural models were assessed from raw item-level data using 5,000 bootstrap resamples. Findings Relationship learning and relational trust are positively associated with relationship performance, and trust strongly enables relationship learning. Contrary to the theorised complementarity hypothesis, the learning × trust interaction is negative (β = −0.092, p < 0.001): learning contributes more strongly when trust is low. H4 is therefore not supported; the pattern indicates unexpected diminishing marginal returns. Practical implications Organisations should combine trust-building with structured learning routines, including mentoring, cross-functional reflection, after-action reviews and role clarification. Social implications Workforce development and organisational well-being policies in emerging economies should strengthen psychological safety and continuous learning to support voice, adaptation and cooperation. Originality/value This study distinguishes three roles of relational trust: a direct performance mechanism, an enabler of relationship learning and a boundary condition on the learning–performance link. It shows that theoretically complementary relational resources can display partial substitution at the margin.