Bede

Your cheeks are beautiful, etc. It is said to be the nature of the turtle-dove that, if deprived by the loss of its mate, it does not unite with another. This suitably applies to the chastity of the Church, which, although widowed by the death of its Lord and Bridegroom, is so bound by His memory—knowing that He has risen from the dead and now reigns in heaven—that it cannot accept the company of others, content with the love of Him alone, to whom it hopes eventually to reach. …

Commentary on the Song of Songs ↗

Bernard of Clairvaux

"Your cheeks are beautiful as the turtle dove's." The bride's modesty is a delicate thing; and I feel that at the Bridegroom's reproof a warm flush suffused her face, so heightening her beauty that she immediately was greeted with: "Your cheeks are beautiful as the turtle dove's." You must not give an earthbound meaning to this coloring of the corruptible flesh, to this gathering of blood-red liquid that spreads evenly beneath the surface of her pearly skin, quietly mingling with it to enhance her physical beauty by the pink and …

Sermons on the Song of Songs, Sermon 40 ↗

Bonaventure

God's wisdom appears most beautifully in the mysteries of Scripture, even more than in the first manner. For if, so to speak, I wish to praise the bride in that she is pretty and truthful: if I simply say that she is pretty and truthful, my heart is not affected very deeply. But if I say: "Thy cheeks are beautiful as the turtle dove's, thy neck as jewels," I praise her marvelously, if only I understand. I praise her not only as being chaste and good, but as being chaste and loving because of her love for her spouse. …

Collations on the Hexaemeron, Collation 2 ↗