Rainbows Not Included

Why is black and grey not included in a Rainbow?
Are they not 
Good enough, not 
Pure enough?
yet, Red is so violent, and
Blue is a show-off.
Everyone likes them, but black and grey go unnoticed. 
"well" they say "black and grey just don't fit it."
I say, "but im grey and i fit"
they look and walk off, the Rainbows.
Not Anymore.
I look. I see Black. 
"Hello"
They gaze back to me, grey.
"Hello"
Together
"No Rainbows Included."
We are alone and together.
Not Seen or Heard
I see White.
"Hello"
"No Rainbows Included."