Justification
Holly worried about being attracted to Artemis. Not the awkward interpersonal aspects, but the ephebophilia. Bad enough being attracted to a human without her being attracted to a youngster. Then one day, it occurred to her: adult Pixies look like children to human eyes, which means human children look like adult Pixies. Artemis even had the right colouring. Only Mulch would call her a pervert for wanting to D'Arvit a Pixie that looked like Artemis. Her libido had simply been horribly confused by his brief period of physical adulthood, and the combination of his current pubescence and Pixie-like appearance.
Cute as the A/H in TTP is, I had to find a way to justify why she appears to be still physically attracted to him when they return to the present. I remember my little brother being 14. He was cute as a button, but not especially manly. Heck, we were the same shoe size then, and my feet are tiny (and he's not exactly a small bloke these days).