If the Song were an allegory of the Lord’s love for his people, it would be a weak comparison. Solomon's many marriages poorly represent God's love and faithfulness (see 1 Kings 11:1–13).
sixty queens: Solomon married many wives through international treaties (see 1 Kings 11:1–3, 8).
Concubines were wives with lower status than a primary wife but higher than a slave. People acquired concubines through war, debt repayment, or purchase.
In the anthology view, mentioning queens and concubines means the woman is more desirable than all others.