Don't misunderstand. This is a 30 year old agreement which we never discussed save for once or twice early on...and once when she was concerned about a particular lady who turned out to be, not a lady, but a girl. (But I mention the incident to allow people to understand, this agreement isn't a figment of my imagination. LOL)
Several of my acquaintances had apparently stepped over the line... but I had not because our agreement included... no mutual friends, no mutual acquaintances. I kept to the letter of the agreement... and probably sidestepped a nasty outcome.
I would be the first to admit that trying to negotiate that kind of agreement after a number of years of marriage would be difficult. We set the guidelines for our relationship early on... and yes, somethings change and mature over time. But I think this particular topic is a difficult one to "renegotiate" especially if you don't already have something in place other than your marriage vows.
Good luck.