I am also part of a new triad. Myself, my boyfriend, and his wife. Yes, there are others involved. I've dated throughout the relationship. Sometimes he's involved, sometimes he's not. He does not date or sleep outside of the triad. She has boyfriends, one who seems to be lasting.
But I'm the first to have joined their relationship, with intentions of being a full member. Where all three of us are there for each other. Committed fully to each other.
I hope in the future that our triad will expand to include others, perhaps her boyfriend, perhaps a wife or husband of mine (at least in a legal sense). Perhaps other girlfriends.
I'd be happy to talk anytime.