Tumbling Angel

This is a poem dedicated to my friend. She is the most amazing person you could ever meet, but her life has been so filled with pain.

Her fingers flowing over delicate keys, 

she plays - all day.

Silence as punctuation,

she plays the story of her life - 

a sad, sweet melody

which rises and falls 

like a tide 

on the ocean of her pain.

My tune is all white

with a smattering of black.

But for her, black keys dominate

with white far and few.

Her tone becomes major

and the melody quickens,

then sudden

falls back

and minor once more rules

with its black keys, 

strange harmonies

- a life reigned by pain.

Author's Note

I'm not sure about various words, and any feedback you could give me would be really helpful thanks. The main words I'm still considering are:
-punctuation
-tune
-smattering
-dominate
-rules