What is the shirk (polytheism/idolatry) of love, and does a person's attachment to a sin, to the extent that he prefers kufr (disbelief) over it, constitute kufr and shirk of love, despite his intense dislike for kufr?

The blameworthy polytheistic love is when a lover equates his love for Allah with his love for others, such that he reaches the perfection of love and submission to other than Allah Almighty. And whoever loves other than Allah with a love of servitude has associated others with Allah. Love is divided into common and special types. The common types are natural love, love of mercy and compassion, and love of familiarity and companionship. These types are not considered polytheism. As for the special love, it is the love of servitude that includes humility, submission, glorification, and obedience. This is befitting for Allah alone, and if a servant loves another with it, it is polytheism. Therefore, whoever's love for disobedience reaches the point that he chooses it over Islam has fallen into polytheistic love and has set up a rival to Allah, and he must repent.