<p>Effective inventory management is critical for firms operating in volatile markets, particularly those with short product life cycles. While the classical Newsvendor model provides a foundational approach for optimizing order quantities under demand uncertainty, it often neglects the long-term implications of stockouts on customer behavior. This study extends the Newsvendor framework by incorporating customer retention—modeled as a function of past stockout experiences—into the profit-maximization problem. We analyze a supply chain with two unreliable suppliers, differing in cost structures, disruption probabilities, and fulfillment reliability, to determine the optimal order allocation that balances short-term costs and long-term revenue retention. Using a stochastic optimization model, we demonstrate that ignoring customer retention leads to systematically underestimated stockout costs, resulting in suboptimal order quantities. Our findings reveal that supplier diversification, while costly, can enhance resilience when accounting for customer attrition risks. The model provides actionable insights for managers navigating supply uncertainty, showing that higher upfront procurement costs can be justified by preserving future demand. This work contributes to the literature on supply chain resilience and behavioral operations by quantifying the interplay between supplier reliability, inventory policy, and customer loyalty.</p>