Since Zoe was Jon's girlfriend because of a wish, she couldn't not be Jon's girlfriend. So Karyn's wish was granted by causing her to possess Zoe's body.
One moment, Karyn was outside in the hall, and the next, she was in bed with Jon. At first, she was pleased that her wish had come true, but when she saw that she was in Zoe's body, she screamed.
Since her "essence" was transferred to Zoe's body, Karyn's body suddenly fell to the floor with a thump, causing the stone to roll across the floor and under one of the bedroom doors.
