Just then the stone flashed and Jon remembered Karyn was a tomboy, not a girly girl, and that they were not a couple at all. Since he did not wish to know who made the wish, he made hasty assumption that the wish must have been made by Karyn, because who else could have done that.
Jon began thinking to himself, why would Karyn do this to her, and not let him remember the changes. Jon was hurt and confused by these changes, and did not know what to do. On one hand, he felt he should confront Karyn about why she would do this, but on the other hand, she was being very hypocritical by make a wish like this that altered him, without letting him know about the wish. She saw him all day, and as far as he remembered, she never told him that she made that wish to be girly like that, he just at the time thought that was how it was always supposed to be.