Hi guys,
I emailed Avron Kulak, my professor from last year who taught Kierkegaard, asking about the latter on relating to relationship itself. This came up in our discussion on Auster and the self-doubling he describes in The Invention of Solitude. Here is what Avron had to say:

"The only thing that I can think of in [Fear and Trembling] that would involve the issue of how we relate to our relationships is the idea of the absolute relationship to the absolute. In the ethical and the esthetic, where self and other collide with no mediating principle to which both commit, either the self is subordinated to the other or the other is subordinated to the self. To relate absolutely to the absolute, and thus to have an absolute duty to God, is to understand that, as Kierkegaard puts it in Works of Love, God is the middle term in any relationship: there is always a standard, one that is neither the self's as opposed to the other's nor the other's as opposed to the self's, in light of which one relates to the relationship.

Kierkegaard does write directly about relating to relationship in Sickness Unto Death: "A human being is spirit. But what is spirit? Spirit is the self. But what is the self? The self is a relation that relates itself to itself or is the relation’s relating itself to itself in the relation: the self is not the relation but is the relation’s relating itself to itself. A human being is a synthesis of the infinite and the finite, of the temporal and the eternal, of freedom and necessity, in short, a synthesis. A synthesis is a relation between two. Considered in this way, a human being is still not a self. In the relation between two, the relation is the third as a negative unity, and the two relate to the relation and in the relation to the relation…. If, however, the relation relates itself to itself, this relation is the positive third, and this is the self.… The human self is… a relation that relates itself to itself and in relating itself to itself relates itself to another." (13-14, Hong and Hong translation, Princeton University Press)

This is a pretty dense passage and it is written in the context of Kierkegaard working out three notions of despair – one in the ancient Greek world (the despair of not having a self), two in the biblical world (the despair of either not willing or willing to be oneself) – and the way in which the self, in order to overcome despair, must not will to be itself but must rest in the power that established it – God, for Kierkegaard. But the fundamental point of the quote is that the self is not the relation – ultimately, the ancient Greek opposition – between the infinite and the finite but is the relating to that relation. If we are just the relation, we are only what Kierkegaard calls the negative unity of what turns out to be two opposed aspects of ourselves. While Kierkegaard characterizes this position as human, he is clear that it is not the true self. In then stressing that the self is the relating to the relation as a relation, he indicates that the self is not just the negative unity – the opposition – of the infinite and the finite but the way in which it relates to that relation. So it is interesting that he concludes that, in relating to oneself as a relation, one is, at the same time, related to, or constituted through, an other.

I am not sure if the passage from Sickness Unto Death helps you much. But I think that it aligns with the idea from FT and Works of Love that a relationship always involves the absolute or middle term."