I did something very similar, I was chatting to an internet friend and he was telling me his wife had closed her legs and he was getting desperate, I had got medical problems and couldn't fuck my wife so I asked him if he wanted to, it didn't take long to arrange a meeting where he just bumped into us and we got chatting, we worked it so we bumped into each other 4 more times she didn't know she was being set up but she had the freedom to go her own way, he was hitting on her and I made it clear that I was happy with it, she just told me outright that she wanted to fuck him , I phoned him that evening and told him to go ahead, I gave him as much information on her likes and dislikes and that she liked it a bit rough at times, he took pictures and sent them to me along with what they enjoyed together, it worked well and she still doesn't know it was arranged 7 years ago !!!.