We introduce Natural Structure Pathways (NSP), a structural framework for characterizing stability and collapse in constrained dynamical systems. Within NSP, stability corresponds to the closure of admissible state transitions under bounded interaction intensity, while collapse is defined as the first violation of this transition closure. Interaction intensity is treated as a generalized measure of externally induced perturbation, and system tolerance emerges endogenously from internal constraint density. This relationship defines a structural stability condition in which persistence is maintained when interaction intensity remains below a constraint-derived threshold, and collapse occurs when this threshold is exceeded. Proximity-induced instability is interpreted functionally rather than geometrically: decreasing separation between interacting systems increases coupling strength, thereby raising effective interaction intensity. Collapse arises when this increase drives the system beyond its constraint-defined tolerance. To illustrate these principles, we present a simplified numerical simulation comparing unconstrained dynamics with NSP-constrained dynamics under uniform interaction conditions. Constraint projection enforces bounded velocity, directional tolerance, and smoothness, producing sustained bounded behavior across a range of parameters, while unconstrained systems exhibit persistent dispersion. NSP does not replace domain-specific dynamical models but provides a scale-independent structural description of the conditions under which constrained systems remain stable or undergo collapse under increasing interaction intensity. NSP reframes stability as a structural property of constraint-mediated transition closure rather than a consequence of equilibrium