Absolutely amazing game so far! Loved every interaction, from the fairy being such a "cowboy" attitude girl to our tomboy friend...
Although I see on the screenshots here a purple-haired girl but I don't think I ever saw her?
Ah! If you mean the picture of the girl with the pink/purple hair and eyes, you can start that interaction in the first room you enter after jumping down into the dirt tunnels.
Near the end of that room, the path splits - right leading to two waterfalls that you hop over, and left leading to that interaction. You'll know you're in the correct place if you see the giant ring:
