Jon wasn't sure they could make it a month without going all the way. But, then a thought occured to her. If they weren't near each other, then there wouldn't be any problem.
He suggested to Karyn that they try to escape and live out in the wild until they returned to normal. They'd have to go in different directions, so that they wouldn't be around each other, but they would be free. Free from Sarah. Karyn thought it was a good idea, but he wasn't sure if they could just leave without Sarah noticing. And there was also the stone. If Sarah still had it, she could just wish them back to her house, making their escape pointless.
So, they'd have to take the stone from her and then escape.
That night, they tried.