Dual Stones

Samantha has always had this rock that she didn't know where it came from but knew it meant something to her so she never let it go. They find out that the other has one exactly like theirs and start to research them. The end up at their family trees and find that the rocks signify your soulmate. They don't want it nor do they believe it but will never let go of the rocks because if the story is true then you damn your partner and yourself if you were to let go of the rock. They find that there is a race that the rocks came from and travel to where the race resides and are given a choice by the chief: drop the stones and go back to live in the world they love, damning yourself and your new-found friend, or stay in the land and end up falling in love, reaching an 'unfriendly' level. And they can't leave on their own. They must get permission from the chief who isn't letting them go anytime soon.