Instructions
Use your airship to fly to Fluorgis, which is on the Ordalia continent. This is one of the towns where you must go to complete "An Earnest Multitude." Go to the pub and accept the quest there so that you can start in Fluorgis.
Exit the Pub once you have accepted the quest, and the quest marker will be added to world map in Fluorgis. Travel to the area with the quest marker to meet the first woman and sing to her.
Go back to the World Map and pull up your Clan Info. Look at the list of quests and select "An Earnest Multitude" from the list. Use the "Dispatch" button to send one of your clan members to complete part of the mission. Follow the prompts to select a clan member. When choosing one of your members to go, look at each one -- if he is jumping up and down, he has a higher chance of succeeding.
Send your party member to complete the Targ Wood portion of the quest. When you are dispatching a clan member, you are given the option to send him to Targ Wood or Moorabella -- Targ Wood is farther away, so the mission will go faster if you dispatch someone there and go to Moorabella yourself.
Use the airship to fly to Moorabella, which is on the Loar continent. When you get to the Moorabella world map, go to the area with the quest marker to initiate the scene between your character and Marnot's lover. Once you complete this scene and your dispatched party member returns from Targ Wood, the quest is complete. Go to the pub in Fluorgis to collect your reward.