So he's demanding that you join him in a unicorn hunt if you want to be poly. Bleh bleh bleh. There are a ton of writings out there about why this is not necessarily the best approach to poly, maybe you could find some and share them with him. Why does he insist it has to be that way? To prevent jealousy? It absolutely will not do that.
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.