Well gosh. 6 years together and now he's a changed man, pushing to involve you in exploring his bi nature.
I've spoken to enough bi men to know there's a population of guys out there who won't be with a man unless a woman is also present. I find it a kind of cop out, but hey, a fetish is a fetish. They aren't rational.
However! He has NO RIGHT to be pushing you, a virgin except for him, to accompany him on this journey of sexual discovery. State his desire, yes. Downplay your concerns and lack of desire for meaningless sex with a virtual stranger? NO!
Has he been watching lots of porn? The internet has brought fetishes to many people's minds and bucket lists. It all looks so easy in porn. 2 hot guys, one hot woman bringing them together, her hands putting the men's bits together, encouraging them. But honey, porn is porn. Real life is real life. You're not a porn actress.
I'd say if he really wants a guy for meaningless sex, he should start cruising and get a guy and do him. Sheesh.
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, F, 60, poly-dating, loving and living with
miss pixi, F, 38
Punk, 41, M
Old Friend, gender fluid
Nick, 35, M (occasional lover)
Hippie, 25 (?)
Dark Wing, 45 (?)