This work develops a formal mathematical framework for relationships, grounded in the observation that every entity—ranging from elementary particles to galaxies—exists within and is shaped by relationships. Maintaining these relationships requires energy, yet no general abstract language currently captures their structure or behavior. The purpose of this paper is to introduce such a language: a unified, set theoretic formalization of relationships applicable across domains, including physics, chemistry, biology, and human interaction.The theory presented here arises from a practical need to supplement the view that reality is fundamentally relational with a rigorous mathematical abstraction. It provides a foundation for classifying and categorizing phenomena by revealing the underlying relational structures that give rise to such classifications. As a new interpretive framework, it is expected that further developments will emerge over time, much as algebra and calculus evolved from their initial formulations. Although general in scope, the theory remains closely connected to counting and combinatorial principles, with set theory serving as the primary tool for achieving maximal conceptual simplicity.