Wow! Tough question. Good answers here too. I was going to give a witty answer with a web reference, but gazillions of poems and short stories exist with that metaphor, simile,or analogy.
Personally If someone set me free I would like to know who it is or maybe I am just lost - LOL. Then, again that may only apply to dove since they mate for life.
What a great hub idea. Birds, mating habits, bird characteristics, and love.