The problem as I see it with "how many partners have you had?" is that it isn't specific enough. I enjoy knowing the details of my partners' other experiences -- past and future. But I don't want to know "four" or "eleven" or "eighty-eight." I want it all.
I want the juicy details. The tales of sexual adventure are both interesting and arousing! Sharing these stories can easily lead to making new ones of your own. Knowing how the other guys looked and felt and tasted just adds the needed detail to make the scene come alive in your head. The story of my wife's first time giving head, or knowing how cute her first real boyfriend in college was, or even that the guy she was dating before me had a bigger cock than I do -- these are all interesting. They do nothing to dampen my enjoyment of life with her.
If, while we're out for the day, she sees a guy and lets me know that she thinks it would be fun to fuck him -- hopefully describing a scene in detail, then we can talk about it and end up horny all day because of it. That's fun and frustrating (in a good way). If she chooses to have sex with another guy, and has the fuck of her life, that's really awesome! I don't wish the same old monotonous routine for the love of my life…I wish great new things for her. Isn't that what true love is about?
I'm glad that I don't stay up nights wondering how I compare to X. I don't have to wonder because we talk about it. If X did this thing with his tongue that she really liked, maybe she can teach me to do it too. My wife and I are friends and we are friends with people with whom we've had sex. I like it. It is a nice and healthy relationship.
It's interesting to see how conservative noders are. In addition to the writeups here, I've had several /msgs telling me how messed up I am.