False. That outcome is FAR from inevitable.
My wife loves BBC. She's had plenty of playmates that absolutely rocked her world, and didn't develop any kind of feelings for them. None have been any kind of threat to the place I hold in my wife's life.
She's also had one guy who she unexpectedly bonded with very deeply, and they became close enough that she made him her boyfriend. We didn't think polyamory was something we were ever looking for, but it turned out to be much better for us than we expected. We were reminded that people don't have a finite supply of love that they have to divide between those they care about. You can have immense love, even different kinds of love, for more than one person. Parents don't stop loving their firstborn ******* when they have a second one.
My wife and her boyfriend became very close, and it was strange at first to hear her say, "I love you too," when they talked on the phone. Eventually it made me smile every time, because I could see how happy she was, and that's all I've ever wanted for her. Recently he found another woman who might be a good fit for a long term primary life partner, which is something we never wanted to block him from, so he and my wife made the tough decision to break things off, for now at least. She still cares for him very much and letting go has been really hard, but she wants him to have the chance to have the kind of happiness that she and I have been blessed with, that comes from a full-time committed relationship with a loving partner who is all-in with him.
What my wife and her boyfriend had went WAAAYYY beyond "seeing how great sex can be" and her taste for big black cock, yet even through all of that, with all the complicated emotions involved, she's never once become even slightly less loving of me, or any less committed to our marriage. In fact, it's very much the opposite. She tells (and shows) me regularly how much she appreciates the freedom our dynamic gives her, he much she values the trust I place in her, and how grateful she is to have a "strong, secure cucky (her words)" who can let her do this without constantly doubting her, or my place in her life.
I know this lifestyle is not for everyone, but I can say with zero hesitation that it has brought my wife and I closer together and made our already strong marriage even stronger AND our sex life hotter and more satisfying for both of us. This notion that white men have nothing to offer a woman if they don't have giant cocks, or that women are universally weak, emotionally immature, or heartless, just because they enjoyed a good deep dicking, is completely false.