What is the symptom of love? The symptom, the prime symptom, most important symptom of love, is that the devotee wants to see that his Lord's name, fame, etc. become widespread. He wants to see that "My Lord's name be known everywhere." This is love. If I love somebody, I want to see that his glories are spread all over the world. And Krsna also says in the Bhagavad-gita, na ca tasmat manusyesu kascit me priya-krttamah: anyone who preaches His glories, nobody is dearer to Him than that person.
From Srila Prabhupada's lecture on Srimad-Bhagavatam 1.2.6 — September 4, 1972, New Vrindavan