Identify a scenario in which it is unclear how to layer two system components that require tight coupling of their functionalities?

A scenario where layering two tightly coupled system components is unclear could involve an online shopping platform that integrates a payment processing system with an inventory management system. Both components need real-time data exchange to ensure accurate stock levels and seamless transaction processing. However, defining the boundaries of each layer becomes challenging, as the payment processor must access inventory data instantaneously while also triggering updates to stock levels, leading to potential complications in maintaining a clean architectural separation. This can create issues in managing dependencies and ensuring system reliability.