Well, if you have discussed it, that helps. If she does it just to oblige your fantasy, that is not good. It really is asking too much of a woman, any woman. However, if she is warm to it at some level, might still happen. My suggestion is to get out and meet real men. Online is generally a dead end. Maybe it works for some, but meet and greet and other events or public night clubs and similar are more natural and a lot of games and fakes/flakes evaporate.
One thing that often works, if it is your scene, is to just go out to a bar or club that has dancing. If there are attractive black men there and you don't enter together or sit together, she likely will be approached to share drinks and dance.
That is the big difference between fantasy and reality. Those men are real, multi-dimensional people, not just theoretical dick life support systems. Some she may find she genuinely likes and finds interest as people and potential lovers.
This is good for both of you. Your wife will, as I have, become pleased to find how sexually desirable she is. You will have a test run against the green-eyed monster. Again, reality vs. fantasy - you will feel an emotional jerking when you are at a distance and someone else is flirting with your wife and maybe has her in his arms on the dance floor.
No guarantees he has a BBC either. My experience has been most black men are hung pretty average. But there are plenty of superb exceptions. Cannot know until they are unwrapped.
Thar said, along the lines of where you were going in the original post, you can stack the deck. If she is going to test the waters, some prescreened BBCs might happen to show up and flatter her with compliments and shower her with attention. If you do this, don't just go on size. Find them at established swinger sites with multiple female reviews to make sure they are courteous, respectful, intelligent, and great in the sack. If she does go the distance, you want her to be wowed and limp away with no regrets. And from your side, be forewarned to be careful what you wish for. Good luck!
