The dynamic nature of supramolecular networks of telechelic polymers offers new avenues for the design of novel materials with enhanced melt strength and extensibility, increased energy at break, or self-healing properties. However, monitoring the kinetics of the underlying molecular-level scission-reaggregation events remains challenging, particularly in high-molar-mass polymers in the bulk state. Here, we employ solid-state 1H NMR spectroscopy relaxation dispersion experiments to investigate the aggregation-scission dynamics in poly(ε-caprolactone) modified with oligopeptide end groups that form one-dimensional hydrogen-bonded aggregates. We have successfully determined the timescale of end-group dissociation directly and independently of any relaxation of the polymer segments at different temperatures in the bulk semi-crystalline and melt state. This site-specific, non-destructive method is applicable to entangled, high-molar-mass polymers without chemical modifications or modeling, provides critical insight into the dynamics of supramolecular networks in the bulk state, and promises to be a valuable tool for the directed development of next-generation functional materials. (Figure presented.)