This article introduces the Model of Authorship and Relational Illegitimacy, a theoretical framework designed to describe a specific pattern of psychological suffering organized not around intrapsychic conflicts, but around a structural experience of existential illegitimacy within relational contexts. The model proposes that individuals internalize a Comparative Relational Field where legitimacy is conditional, based on performance, hierarchy, or external validation. This generates a persistent need to justify one's own presence, manifesting as an "Alibi Structure"—a defensive organization sustained by shame. Clinical observations suggest that therapeutic transformation occurs through the progressive recognition of the authorship of one's own being, rather than the restoration of comparative legitimacy. This manuscript presents the conceptual architecture, regulatory circuit, and preliminary clinical markers associated with this transition.