My wife has had a negative view of bi play, but didn't seem such a big deal to me. Our first swinging experience was with a couple, and his wife wanted to eat my wife while I fucked her, and my wife sucked her husband. Afterwards, my wife said she didn't care for that. Next experience, different couple, without asking, his lady dove in to eat his pie from my wife, while he grabbed my cock and gave me a suck. Made my wife a bit angry...
Then we met a single guy, who is bi. Him and wife were in a 69, and i was fucking her from behind. then stopped for a bit, went to kiss her. She took his cock out of her mouth, we kissed. After, figuring what the heck, grabbed her hand, which was holding his cock, and guided his cock to my mouth, and started sucking. Then we both sucked on it. On the way home, she told me that made her "hot"... We've been back to his house 3 more times... lol