Apples and Boundaries

I think that some words are like apples:

An apple enclosed in its skin,

hides flesh glowingly beautiful,deliciously succulent

But - when that same substance is exposed to the air,

public for all to see,it becomes -

Darkened. Ugly, Putrid

So too, there are words,

so beautiful and enticing,

in a private skin enclosing two alone,

But - when used beyond that magic line, are-

Darkened, Ugly, Putrid