How do I convince my wife

24M here with black 22 wife. I love her so much but I would love to see her get fucked my another man. I’ve talked to her about this multiple times and she always says that she would not be interested and doesn’t fancy the idea at all. Strangely enough, she likes imagining threesomes and cucking with imaginary characters but cannot get behind cucking in real life. How do I convince her to at least entertain the fantasy?