I was googleing around and found this :
"The Serenade of Love is only used to increase rapport with some NPCs.
This song is a reward for the quest “Relationship Guru,” which starts on the island of Liebeheim. This mission involves talking to some NPC and sending love letters. After this simple quest, players receive the Serenade of Love."
However i went Liebeheim island and had no such quest there ? what im i missing here ? any insight would be helpful thanks!