According to the Jewish Study Bible, introduction to what is called there the Song of Songs:
"While the book's origin remains obscure, the history of interpretation of the Song in Jewish tradition is well documented. From as early as the 2nd century CE, it has been understood in both human and divine terms. In rabbinic tradition, the Song narrates the words which God and Israel spoke to each other at the Red Sea, at Sinai, or in the Tent of Meeting. The descriptions of the male lover are understood as allegorical descriptions of God while the descriptions of the female lover are understood as divine praise of Israel...."
And, not surprisingly, many commentators read this book to be about human sexual love. In this passage, for example, it's spring, the couple enjoy each other, and they want to be together.
Many Christians interpret this book, as well as the rest of what we call the Old Testament, as foretelling our relationship with Jesus Christ. For example, according to the Wesley Study Bible, Wesley asserted that this particular passage describes how the church triumphs in Christ's love and gracious call. That reading suits the lectionary pairing with the passage from Matthew this week. Jesus says, "Come to me, all you that are weary and are carrying heavy burdens, and I will give you rest.
(amended from August 2009)