Polymer membranes are critical functional components in proton-exchange membrane water electrolyzers (PEMWEs), where they simultaneously enable ionic transport, separate reactive gases, and sustain mechanical loads. Despite their central role, membrane failure remains a key limitation for system reliability and safety, driven by the complex interaction of electrochemical reactions, two-phase flow, transport processes, and material degradation due to mechanical, chemical, and thermal loads \cite{wallnoefer-ogris2024}. In particular, gas-liquid flow regimes in catalyst layers, porous transport layers, and flow channels strongly influence local pressure, temperature, and concentrations at the membrane interface. These impact the membrane’s hydration conditions, inducing heterogeneous swelling, stress concentrations, and membrane thinning, which accelerates the aging process. This contribution presents a multiphysics modeling framework for the simulation-based investigation of membrane degradation and failure mechanisms in PEMWEs, synthesizing ideas from previous works \cite{antonini2025,chandesris2015} into a novel integrated modeling approach. Two-phase flow in the adjacent porous and free-flow regions is described using porous-media formulations and phase-field computational fluid dynamics, resolving gas generation, saturation, and pressure fields under different operating conditions. The resulting interface quantities are coupled to a porous-mixture-based finite strain membrane model that accounts for hydration-dependent transport and swelling-induced deformation. Damage or failure indicators are introduced to capture the onset of critical membrane degradation driven by cyclic loading, dehydration, or pressure fluctuations. This modeling concept enables systematic analysis of how operating conditions and flow regimes, including annular or mist-like patterns \cite{sangtam2023}, contribute to membrane stress and failure risk. The framework provides a foundation for predictive lifetime assessment and supports the design of more durable and safer electrolyzer systems.