"... isnt it natural for women to become attached and form a loving bond. I know theres exceptions, those who can comfortably keep an emotional distance, but I think this isnt the majority. Also Im not sure most women would have the cognizance to know in advance that they couldnt keep it casual because most have never tried."
Poly relationships are not casual, or, rather, they can be deeply loving relationships that are anything BUT casual. If you want to be poly expect all the emotional engagement, risks, turmoil, and rewards that you would find in any loving relationship.
That is an answer to your question about superficiality, too. Poly relationships are not superficial, and do not indicate superficiality in the people who engage in them.
"She means so much to me, and is so special to me, yet I feel compelled to seek out other people to have relationships with. ... Is it worth losing a true love, and best friend to find out if poly is for me?"
Well, you have named the horns of your dilemma and you see them clearly! Unfortunately -- or perhaps fortunately! -- you are the only one who can deal with them. If you truly love her and believe that you two should go on forever, and she cannot accept poly, then you both must make choices. Be mindful, aware, and make your choices well.
As a couple you might, at some time in the future, look into attending a workshop or seminar on poly or on alternate relationships. I think you should not try to convince her of anything; instead you might present it as a way for her to educate herself in how you feel, a way for her to understand you more deeply. In time she might change her mind; she might not. But at least she will know that you are not abnormal or a potential cheater, and that there are people who live in loving relationships that are not monogamous.