My Two Cents
First of all I would caution you to take only what I have to say with a grain of salt. As I myself am realtively new in the exploration of Polyamorism, my insights are still nacent and developing.
You are curious about WHAT it is to be polyamory? I am not sure if it is a matter of mind set, view point or a genetic disposition. However, I would say that it is a point of being able to love more than one person comfortably, openly and unreservedly. The nature and depth of that love can be different from partner to partner, but then again... are not all relationships unique?
I could never begrudge a person that was stead fastly monogamus. And in some ways I would hvae to say that I would envy that person. The difficulties of choosing? accepting? giving in to? (is there really a choice?) the polyamory lifestyle can be numerous. And It is not something for the faint of heart. And yet again, does it diminish it to call it a "lifestyle"? I think so.
I would guess it comes down to the ability of a person to SHARE their heart. openly and honestly. To be willing to see and appreciate and LOVE more than one person for the uniquness of their gifts and the flavor of the affection that can be shared. It is not in everyone to be able to SEE that loving more than one person at a time is possible. And yet it is not everyone that can devote themselves completely to just one other.
To be poly in my mind is to be EAGER for the chance to open ones heart and mind to others while yet being involved in a loving relationship allready. To some how have this, urge to reach out and WANT to love others without reservation while cherishing the love that is allready present.
Well, that is my two cents. I wish you well on your quest. And I hope that in time you will discover the answers you need to help you move on in your life for the pursuit of that which will satisfy and sustain you the most.
If there is no Heart, the mind will never matter.