I select them and get her approval and reach out and set up a lunch date for us to talk and meet quickly. If there is chemistry and attraction then it moves on to allowing him and her to text and then setting up a date night for us all to hang out.
If that goes well then we set up a hotel room meeting that night or another weekend.
I start off by telling him we are looking for a long term friend and partner for us and would like to hang out and have fun. But I cannot please her and we are looking for the right fit partner to satisfy her for me and fulfil that role in our marriage while exploring and respectfully figuring out how we all best fit with each other regarding dominance, my role, his role with her and I and having fun exploring where it can go. And if it starts to not be fun, then its over. She is the boss and he must respect our rules and life and we will do the same for him, allowing the relationship to grow and change organically.
We also establish what we dont like/want up front before the meeting and ask him the same...
And then tell him at first once its over he leaves unless invited to stay longer. Condoms are provided unless she removes it or asks him too.
It usually works out, sometimes it doesnt.
She has met bulls on her own and brought them home and didn't tell me until I came home from work or a trip and there this guy was, in our living room with her, chilling, and her acting like he was a friend but we both knew why she invited a stranger over to our house or let me know she at a new friends apartment and might be a little late coming home...
But its usually my job to pick out her lovers and introduce them and pay for everything until we get comfortable enough to invite him over instead of meeting at a hotel.