I have seen this happen to my own wife.
When I first proposed hotwifing to her, I was interested in seeing her with black men and she frankly thought it was a little weird. But she WAS interested in having fun with other men and wanted a variety of guys, any race was cool with her.
But we had some really disappointing first experiences with guys (most were white) in the beginning. We were complete newbies and kind of rushed into things and didn't investigate guys very well. We learned to slow our roll a bit and made personality a much higher priority in selecting guys.
But then we met a really cool guy from Kenya and he rocked my wife's world! He took his time with her and made her pleasure his priority. He also had amazing stamina and can easily go 30 minutes or longer but made sure he didn't wear her out.
After him my wife would go on Tinder and I quickly noticed that she swiped right on fewer and fewer white guys. Now, two years later she hasn't spoken to another white guy at all. For my wife, personality is still the most important thing in a guy to play with - but she has found PLENTY of smooth talking, charming intelligent guys engage both her mind AND body.
We never use the term "BBC" because we're interested in the whole person, not a walking dildo. She has never mentioned the change in her preference, but it's pretty obvious. But the other night when we were dirty-talking she did let slip a little clue. She was talking about one of her 3 regular guys and said "I can't wait for him to slip his black cock deep inside me again..." She had NEVER made a reference to race or color before that!
I'm convinced her interest in black men is mostly because I'm very Irish and they are just very different from me and that's the kind of variety she is wanting. But there is no denying that her black lovers fuck her much better/longer than the white guys she tried before. Sure, plenty of white guys are also great in bed, but she has found what works for her.
My wife has also said size doesn't matter to her, but the guys who get asked back for a second date are very well endowed and she is constantly telling them how amazing they feel and how full she feels.
She has a date tonight and it will be the 4th time in 10 days that she has been with a black man and she literally can't get enough!
I think we ALL know what is going on here, right?