Leslie Hill in his very lucid book on Blanchot explains Blanchot's third type of self/other relations in the following manner:
In this relation of the third kind, the Other is thought not as another Self, but as radically different, irreducible to the One or to the Same. This type of relation occurs, so to speak, beyond the horizon of world and being; it is relation without ratio, adequation, equality, symmetry, or reciprocity. This is relation without relation, relation in the form of a pure interval belonging neither to being nor non-being, irreducible to all thought of truth, visibility, veiling or unveiling, and figurable only as non-reversible dissymmetry, as a strange space in which the distance from me to the Other is not the same as the distance from the Other to me. Here, all topographical continuity is abolished.
Leslie Hill, Blanchot: Extreme Contemporary (1997)
What makes me so uneasy is the phrase above: "a strange space in which the distance from me to the Other is not the same as the distance from the Other to me." The physical reciprocity of distance can't hold. This makes any approach impossible. An eternally parallel world of discommunication?