Anyone who can't take a "no" with some modicum of grace is not a good or even a safe person to have as a partner. Better that he learned this now, before they got too deeply involved. It sucks that he's hurting, but I have no compunctions saying it's for the best.
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.