I have always known that I'm polyamorous, and I want to try an arrangement with my girlfriend but she cant stand the thought of me being with other people, sexually or emotionally. I've tried to explain my intentions, and that me seeing others will never lead me to not loving her, but she refuses to give it a go. We've been at a loss for quite some time now. Any thoughts?
My thoughts are that you are, as you put it, "at a loss." She "can't stand the thought" of it and "refuses to give it a go." There are no magic words you can say to change her mind about that. For some people, polyamory is just not a healthy and fulfilling choice.
If a polyamorous arrangement is critical for you, then this relationship won't work out. Couples run into 'dealbreakers' all the time - one wants kids, the other doesn't; one wants to move to Iceland and become a goat farmer, the other doesn't.