It is my understanding from what I have read thus far that the concept of social and divine love is the relationship humans hold with each other and with society as well as their connection with God and the universe.  God is a divine and infinite love.  Social is the love held with one's self and others.  Then there is man's love of God which was quite prevalent at the time.
My impression was that the clergy protested because of Pope encouraging humanity to question this concept and because he tied a sense of individual love and happiness to something that was supposed to reign supreme within the hierarchy.