Any islanders in here ? where do i get Serenade of Love song so i can finish Azure island questline

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!

If I remember correctly the questline starts in arthetine‘s main city, there should be a purple quest in the ?business district? i think (the District in the south West).

Thank you i will go there check it out , that might be it since some quest lead u to another locations , thanks again