You are the best in my life, 
but the worse too
You are the sun on my sky,
but the cloud too

You are the fire in my heart,
but the rain too
You are the light in my room,
but the darkness too

Ref:

So let me in, or let me go
or let me understand your show,
Let me feel. or let me fall,
give me the key, or build the wall!

You are the stars of my night,
but without moon
You are the water of me desrt,
or it is a loom
(I dont know)

You are the page of my book,
but you are rough
I`m with you like a bird,
but not high enough