This paper shows that once space is understood as relational geometry rather than a background container, cosmological expansion can no longer be interpreted as motion through space or the stretching of an independent substrate. Instead, expansion is derived as the redistribution of relational accessibility within a closed continuity whose accumulated constraints cannot be discharged externally. Large-scale separation, redshift, structure formation, and horizons are thus reframed as different expressions of one process: continuity-preserving coherence by reallocating accessibility across relational geometry.