I'm not anywhere near being an expert on poly relationships, being new to this myself, but I do know that you can't /make/ someone do anything. My only advice is to calmly, rationally explain to him how you feel. After that it's up to him to decide what he wants to do.
From what I understand, this is the problem with unicorns and unicorn hunting. And, yeah, I'm in a triad right now so I'm learning about this as I go.
I have already resigned myself to the idea that if I don't make a real emotional connection with Lovely that Bear might decide he wants to continue a relationship with her even if I don't. That is just something one has to face if one is going to be poly.
Sorry I couldn't offer more help.
Pinky, 41, f, bi. Married to Bear, 42, m, straight.
Not dating anyone right now.
I became insane with long intervals of horrible sanity.--EAP