Watching my wife

My wife and I met when she was 18 and I was her first real boyfriend. She had never been with another guy before. We’ve been married ten years and often joked about her trying something with someone else. To me it was an actual fantasy but I really wanted to be in control of it. During a night of drinking she brought it up and I told her I’d actually really like to see it happen. We planned to go out the following week with a mutual friend of ours, but originally didn’t tell him our plans.