This article considers the conceptual significance of relationality in Sappho. It argues that Sappho's poetry reconstitutes systems of relation by making evident exceptions to their explanatory capacity. These exceptions can be profitably understood through the rubric of the “event.” Drawing in particular on the relational function of prepositions and Alain Badiou's philosophical work on the event, the article examines how “thinking prepositionally” alongside Sappho reveals both the relations that make up the situational world of her poetry as well as those evental moments of non-relation through which that world is impossibly transformed. The article concludes with considerations of Sapphic fidelity—that is, how Sappho's poetry realizes the transformative potential of the event—and the poet's articulation of the event through figures of preeminence and comparison.