Originally Posted by Silas
We are going to talk again in a few days. I am afraid of losing her and finding out that she was right and that I was just confused about all of this.
Before this conversation I had been feeling a deep sense of self-assurance and trust about my desire to be polyamorous. Will this really be worth it? How can I know?
You didn't lose her, she lost you. The problem is that she has grown up in a world of assumptive monogamy, and few are able to stand outside of their cultural assumptions and evaluate their personal values on the merits only.
Not her fault, and not yours either. Unfortunately human brains are wired to look for blame and assign guilt. So you've imagined, or been force fed, the old tired line that you're selfish, or hedonistic, or uncaring for choosing a poly life rather then the self-denying, sacrificial life of artificial monogamy.
To date, there is no evidence for any long history of monogamy in human cultures, and actually some indicative evidence for just the opposite. It's also natural to have self-doubt about the choice you've made, but when you look at the evidence, just the evidence, monogamy starts to take on the appearance of a death sentence rather then some fairy-tale story (at least for some).
If you want to explore more about the subject their are books like Sex Before Dawn which, for me, was the nail in the coffin for monogamy. So armed with all that, you shouldn't feel a shred of doubt about who you are. And don't let anyone make you feel guilty for being who you are. If anything, get angry. Works a lot better then guilt.