I can see a lot of possibilities for using these rings as seeds for adventures. Two young and foolish (and rich) lovers contract with the PCs to find these rings, which have been around for a hundred years or more and play a role in many a Bard's song. This complicates things later on when one is abducted for ransom during their first anniversary. The other disappears shortly afterward (teleported) but not before pleading with the adventurers to come to the rescue.
Just having the players investigate all of the old tales in order to track down this one-of-a-kind item would be fun. Especially since so many of the original details would have been changed to make the stories more exciting and romantic. And perhaps the rings' powers have changed over time based on the attributes of their owners.