It is about the colors perceived by the poet.

When the blue is the warmest color
It is eternal love.
When the green is the coolest color
It is the fear-free aura for the lovers.
When the red is a burning color
It stops dead all the romances.
When the white is a pious color
It is godly all around.
When the black is the haunting color
It is the ghostly sex of the engagement.
When the pink is the serenading color
It is the butterflies of love dancing all around.