Why is the Moon so lonely?

Cause she has an other...

"And every night, they would wander the skies togheter.
But, one of the other spirits was jealous.
Trickster wanted the Moon for himself.
So he told Kuekuatsu that the Moon had asked for flowers;
he told him to come to our world and pick her some wild roses.
But Kuekuatsu didn't know once you leave the spiritworld,
You can never go back!
And every night, he looks up in the sky and sees the Moon and howls her name.
But... He can never touch her again."