Melemele Meadow

Since there's nothing else on Route 3 and you see Professor Kukui asking other people near the bridge about Lillie being missing, you decide to look elsewhere. Somewhere on the side of Route 3, you spot another area, with a sign saying: "Melemele Meadow: A paradise where the Oricorio dance". Thinking that Lillie might be there, you head in.

And sure enough, you are right, as you see Lillie standing near a field of yellow flowers, scanning the horizon, as if she's looking for something.

"Ah, there you are," she says to you worriedly, "Nebby ran off into the meadow over there..." In the distance, you can see Nebby just beyond multiple fields of yellow flowers. "It did something on the bridge and came here immediately. I hope no wild Pokemon attacks it, I don't remember it learning any moves as defense..."