You are the most handsome of men; grace is poured upon your lips; therefore God has blessed you forever.
The overflowing spoken of in Psalm 45:1 was translated by Calvin as boiling over, since the Hebrew word רָ֘חַ֤שׁ literally means to bubble or boil. I think a better translation in English would be, My heart gushes, since that is what we say we do when we heap praise upon somebody.
But upon whom is praise being heaped in Psalm 45? It is thought that this psalm was ostensibly about Solomon, which Calvin acknowledged. But he had a different theory as to its true subject: "The Holy Spirit is not accustomed to inspire the servants of God to utter great swelling words, and to pour forth empty sounds into the air; and, therefore, we may naturally conclude, that the subject here treated of is not merely a transitory and earthly kingdom, but something more excellent."
In other words, the earthly king is a type for Christ, the Ruler of an eternal kingdom. Thus the words of the 45th Psalm are spoken not directly to the king, but indirectly with Christ as intermediary. In Life Together, Dietrich Bonhoeffer said something similar about how Christians are to interact:
"Human love is directed to the other person for [their] own sake, spiritual love loves [them] for Christ's sake. Therefore, human love seeks direct contact with the other person; it loves [them] not as a free person but as one whom it binds to itself. It wants to gain, to capture by every means; it uses force. It desires to be irresistible, to rule... We have one another only through Christ, but through Christ we do have one another, wholly, for eternity."
Help me to know my sisters and brothers not from a human point of view, Lord, but as fellow objects of your love. Amen.