I do believe it's not easy, much like finding a needle in a haystack. I've talked about the FWB I have who is interested in this. I don't think things will progress with her, she is a flake, honestly, and flakes out even when it comes to just coming over so we can have fun together. She asked to start talking to some black males, I worked to arrange it, and she wouldn't reply to their emails to her. I think she just really gets off on the idea.
All that said, if she wasn't a total flake, she could be one that would progress into a relationship with me. I provide the financial security, love, affection, someone who matches her intellectual level, and without penetration, I can make her cum like she's never cum before. Meeting black men would be icing on the cake of our sexual relationship, not a replacement.
I have another FWB (who is not a flake), who is a major sub, and I can fall into the role of being dominant whenever I want to, and that has a far better chance of being a sustaining relationship for me.