So many factors here being addressed by others, I'll just focus on one or two.
You two haven't known each other all that long. But he's over his NRE for you and is just treating you as the solid gf waiting in the wings to have sex with any other woman he chooses. What the...?
He wants you to meet his new squeeze, and expresses clearly he hopes for a sexual spark between you girls so he can get his 3way jollies.
I take it he's the Dom in the kink he enjoys? Um, there's this term, dom-ass. A good Dom looks out for the feelings of his sub(s). A bad one just wants to be bossy, and get off, ignoring the feelings of others. Could you trust this guy to not accidentally hurt you, physically or emotionally in a kink scene, if he can't even respect your wishes for him to talk about New Girl less, and not answer her texts, when on a date with you? I doubt it.
I am sure you'd prefer your new love relationship to be more fun and easy. But he's acting like a douche... I know he has good qualities and you love him, but in this so-called poly area, he's got some growing up to do. He's thinking with his dick.
Love withers under constraint; its very essence is liberty. It is compatible neither with envy, jealousy or fear. It is there most pure, perfect and unlimited when its votaries live in confidence, equality and unreserve. -- Shelley
Mags (poly, F, 61) loving miss pixi (poly, F, 39) since January 2009, living together since 2013
also loving Punk (42, M) since Oct 2015 (he has recently downgraded us to friends)
"Master," (mono, 34), miss pixi's Dom for 2 years