I like your intro. I am also a gamer.
I am the hubby in a trio (would be ND's role in your trio).
Reading it allowed me to see how our 3rd would feel, and he has felt alot of what you expressed. He gets very jealous of my wife's attention - but not towards me. I think what you are feeling is perfectly normal.
We've been working on our trio for a few months now, and I see us as still very new.
Good luck in your relationship & endeavors!