I've been posting on my blog about feeling jealous or not jealous about my loves possibly sleeping with other friends too, as it happens. I think the thing to do, for both of us, is to look at their actions. Rory has taken big steps, had hard conversations, made herself very vulnerable, and put a lot of thought and work into having you in her life, just as Gia has for me. Love will always be a bit ineffable in the abstract, but actions speak loud and clear.
Congrats on your revelation!
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.