I tried two different times with both of my former wives and it doesn’t, or didn’t work. I think the ‘suddenness’ and the ‘catching off guard’ harms the moment. If you’re not careful, you definitely run the risk of losing her trust - and that’s not easily returned.
For both my wives, I finally admitted my fantasy and was quite surprised of their response. My first wife, I was never able to watch (unfortunately) but we did have some great role play. My second wife - I was honored and thrilled to be able to have watched her with two different black men on three separate occasions; not to mention the meet up with four other black men that didn’t quite click for bedroom time.