I'm confused from your post. Are you a couple looking for a single girl to date the two of you? If so are you expecting her to not date others as well?
Those could be part of your problem. I don't know what you mean about not finding romantic polyamory because the amory part of the word does stand for love which generally includes romance.
I think more information needs to be provided in order to actually help you out.
Woodsmith: My fiancee
Primal: My boyfriend
Star: Possible new girl.
Lamian: Primal's wife
Darkeyes: Lamian's Boyfriend
Siren: Lamian's girl dating
Peaseblossum: Primal's ex-girlfriend
Aiden: Star's Husband