"Oh my god, Karyn! What have I done?" Jon said, looking down at what Karyn had become. He grabbed the stone, which had fallen to the floor, and said "I wish I knew if Karyn could communicate with me." The stone glowed and Jon got his answer. Karyn couldn't communicate with him, because Karyn was no longer human. She was just a penis. And penises aren't sentient.
Jon collapsed onto his bed. He couldn't reverse wishes, so he would never get Karyn back. His friend (and potential girlfriend) was now gone and could never be back.