The closest I got was a few months ago. Her lover encouraged her to tell me to eat her pussy after they had sex. I had never been directly involved in her sex life but that night, while he was visiting for the weekend in our home, she told me to come in our bedroom. I entered the bedroom and they were cuddling, naked under the sheets. Stacey told me to eat her pussy. I was apprehensive having never contemplated eating her creampie. But I did as told. Crawled onto the bed - pulled her sheet down and started eating her pussy. It was swollen from their fucking and soaking wet from her juices. But once I started licking her with my tongue his cum started flowing from her pussy. I couldn't see it but I could taste it - thick with a unique taste. I lapped her pussy and did a good job cleaning her out. She came as I ate her pussy. When she came - he politely told me to leave them alone - which I did. It turned out to be a good experience though I never would have thought so. Went to my bedroom and beat off. Whew.
It's been that way for our entire 40+ years in the lifestyle. She's too self-conscious when I'm present. Started back as newlyweds when we were swinging. Wasn't something that she liked so I didn't press. As we evolved to a hot wife thing I was involved in vetting a lover and helping her prepare, I wasn't directly involved in their sex. Would have kept swinging but the same issues with my small penis size and inability to last a decent amount of time before cumming put a stop to that - hence our relationship of her being allowed to have sex.