What is Love?

What is love? 
The hearts desire?
Does it last forever?
Does it quickly tire? 
Is it shared smile?
A mental obsession?
A racing heart?
Undivided attention?
To me...
It's an expert thief
For it steals my eye
And is quick to leave
As I hold my breath
My once fickle foe
Quietly whispers 
My breath has to go