A very simple achievement to unlock. In the chief's home in the jungle town of Lekora, there is a woman who says that her wedding ring was taken by the monkey enemies in the jungle. This quest is not technically added to your quest log, but after speaking with her, you will be able to complete this quest.
All you have to do is fight the monkey type enemies (with the purple flower on their backs), until they drop the Wedding Ring. It will be randomly dropped in one of the orbs the enemies drop after the battle ends. After you've obtained the ring, return it to the woman in Lekora to unlock this achievement.