The titles of Russian nobility were formalized by  Emperor (Tsar)  Alexander Ill. The title Grand Duke belonged to sons and paternal grandsons of Tsars. Grand Duchess correspondingly to daughters and paternal granddaughters, as well as legitimate wives of Grand Dukes.

Russian aristocracy more distant from the Tsars Emperors were titled Princes of Russia. Lubovedky was thus related in some way to one of the Tsars. However, more likely we should take the reference allegorically, and think in terms of him representing a high component of the psyche.

See https://en.wikipedia.org/wiki/List_of_Princes_of_Russia