My heart overflows with a pleasing theme;
I address my verses to the king;
my tongue is like the pen of a ready scribe.
—Psalm 45:1
Many solid commentators, especially the older ones, argue that Song of Solomon is about Christ and the church. I don’t think that theory makes it all the way down the aisle. I also don’t think it is necessary. You don’t need to make Song of Solomon about Christ and the church because marital union and communion between husband and wife are already an analogy of Christ and the church. The Song of Songs is about that which is about Christ and the church.

The 45th psalm is also “A Love Song.” It is utterly unique. It is a song of praise for Israel’s king on his being wed to a foreign bride. How did a royal wedding song make its way into the hymn book of Israel?
The psalmist tells us he was inspired. But is this the Shakespeare kind of inspiration or the Spirit kind of inspiration? Why not both? The psalmist takes up a pleasing theme that then takes him up. He takes up the pleasing theme of love between a man and a wife, and then that theme takes him up to the reality that stands behind it. The God-designed analogy is used by the Spirit to testify of the Son.
Song of Solomon is limited to earth, but the analogy it speaks of is not. Here, the analogy reaches such a fullness in the king of Israel, that the transcendent is touched. The King is God (v. 6). Derek Kinder says this “is an example of Old Testament language bursting its banks.” In the 110th Psalm David sang, “The LORD says to my Lord: ‘Sit at my right hand, until I make your enemies your footstool.’” There, Yahweh addresses one who is David’s Lord. Here, this same Messianic figure is not just David’s Lord. He is God. And God (the Father) anoints God (the King). Hebrews 1:8–9 leaves no doubt as to who is the only one who could fulfill such language. “But of the Son he says, ‘Your throne, O God, is forever and ever, the scepter of uprightness is the scepter of your kingdom. You have loved righteousness and hated wickedness; therefore God, your God, has anointed you with the oil of gladness beyond your companions.’”
Understanding this, consider the “plot” of this wedding procession. The King is the most handsome of the sons of Adam and He is God. Having put on the glory of conquering the foes of God, the King then takes to Himself a foreign bride who is called on to leave her people.
The Psalmist here is inspired, but not to make an analogy of this wedding. He is inspired, but the analogy that is marriage reaches its greatest earthly heights in this wedding of the King of Israel; heights that can only reach their fullness when the King of heaven is born in Bethlehem as a Son of David: the most handsome of the sons of Adam, God and King, victorious, and taking a foreign bride.