"It must be the stone," Jon said. "Somehow, it took away a year of my life."
"Wouldn't I remember?" Karyn asked.
"You appeared after I made the wish for you to appear. So you didn't hear the wish," he said.
"Well, I wish you remembered the same reality I remembered, as well as the current one, and knew what was going on," she said.
Suddenly, Karyn vanished, as things changed again in the room, this time more drastically. "What the ..." Jon said, as the stone dropped to the floor with a thunk.
For some reason, his bedroom looked quite different than normal (or what he perceived to be normal, thanks to Karyn's wish). He knew that she had made a wish, that obviously had caused her to lose a year of her life, just like what happened to him, but at the same time, he felt like they were supposed to be the same age and both sophomores in high school. Thanks to Karyn's wish, Jon was now more confused than ever, having multiple viewpoints on what should have been the "real" reality. And on top of that, he now knew why each wish was taking away a year of the wisher's life. It was a different stone - the Immaturity Stone, to be precise. Someone took his stone and replaced it with this one.
After making her wish, Karyn suddenly disappeared and reappeared somewhere else, without the stone.
"What happened?" she asked aloud, noticing that her voice sounded a little more high-pitched than usual.