The guy who wrote the lyrics is a hopeless romantic.

He is singing about a girl he saw in a hallucination/ dream.

He enters the forest- which is no ordinary forest. "Happy forest" basically: (Come closer and see see into the trees find the girl while you can ).

Her voice was so enchanting- like a siren (I hear her voice calling my name the sound is deep in the dark).

When he awoke into reality, he realized he is in love. He then goes on a quest to search for her and finds nothing. He becomes hopeless (I'm lost in a forest all alone The girl was never there)

So now he's searching for her in reality but all the other girls are not "The Girl": (it's always the same I'm running towards nothing again and again and again)

I hope Pygmalion found his true love.