Denys Turner notes that the Song of Songs presented challenges to the “minority” of medieval theologians who argued for a more rigorous grounding of spiritual in literal senses.  For these, the text speaks literally, referring to specific events; and these events, as Thomas says, providentially typify future events.

To qualify as a type, though, an event would not only have to have some formal similarity to the fulfillment in Christ, but should participate in the history that leads to Christ.  The exodus not only has the same shape as redemption in the new Moses; it’s also the case that “without exodus, no Christ,” since the exodus is a means by which Israel is shaped to be the people that would receive the Messiah.

At the same time, these theologians didn’t want to say that the actual love affair between Solomon and the Shulamite (about whose marital status the Song is ambiguous) was the literal referent of the Song.  That reluctance had two roots: First, literal human sex was too vulgar to serve as a type of redemption; second, the love affair depicted in the Song has no apparent causal relation to the incarnation.  Human eros is thus “image” rather than “likeness,” and this puts pressure toward “metaphoricism” or sheer allegory over against typology.

They’re caught between their disparagement of sex and their desire to be literal.  One way to handle this (suggested by Nicholas of Lyra) was to say that the literal referent of the Song is not a love affair but Yahweh’s dealings with Israel depicted as a love affair.  The other, and more common, escape was to ignore the historical referent and instead mine the Song for metaphors of spiritual life: The tensions in hermeneutics forced them to be more allegorical in practice than they could justify in theory.  Ultimately, it’s not the love of this man for this woman that typifies Christ love for His church, but only human love in general.