If you are married, the [[Old Mariner]] will appear, but will not sell you a Mermaid's Pendant. If you get divorced, you can purchase another one, which can be given to any romanceable [[Villagers|villager]].
If you have attempt to give the Mermaid's Pendant to someone who does not have 10 hearts, it will say that the villager is not ready to marry you right now.
The Mermaid's Pendant cannot be sold.