My question is a bit off topic, but I wonder...
Why are only cuckolds kept in chastity. Is no Black Bull keeping his white slut in chastity to prevent her fucking her husband or boyfriend or to protect her getting pounded by other Black Bull or to prevent her from masturbating in order to keep her at a high sex drive level?
In my long-winded response above, I forgot to mention that one of her bulls did tell her once that she wasn't allowed to get off without his permission. While they were fucking, he was really verbal with her, having her beg him to make her his slut, asking her who her pussy belonged to, etc. She said it was his in the heat of the moment, of course. But she was surprised when, as they were both getting dressed and kissing each other goodbye, he told her, "no using my pussy without my permission."
It only lasted for the 2 weeks until their next playdate, and it was just the honor system, no hardware involved. It was hard for me at first, because so much of my self worth in our relationship comes from getting my wife off, but he patiently dealt with my outburst, validated my emotions, said he understood that it would be hard at first, but reminded firmly, "your wife's pussy belongs to me now." He also assured me that I'd still have a role. He told me to continue serving her, and that I should still eat her pussy as often as she wanted, I just wasn't allowed to fuck her or make her come without his permission. He told me to edge her for as long as she wanted, but only to let her finish if he'd explicitly given her permission to come. That turned out to be really fun for me. It had never seemed authentic when we'd tried to switch roles as dominant/submissive before, but this was a way for her to experience the kind of tease and denial ******* she's always put me through, and an opportunity for me to turn the tables on her a bit without breaking role and being a bad sub.
As it turned out, he never answered texts in time to let her come when she asked him. To this day, I don't know if that was part of the game, or if he really didn't get her messages in time, but she went the entire two weeks between their encounters without a single orgasm and tons of teasing. He did tell her I couple fuck her once, but that time he told her straight up that she wasn't allowed to get off.
Of course she was ruthless with my denial when all of this was going on as well, but I was far more accustomed to it than she was. It made her crazy. The changes in her behavior during that short period were astounding! She was ALWAYS horny. She's immediately comply if she was at work and he said he gave her orders, excusing herself to the bathroom or her car to get half way undressed and send him naughty pictures, etc. He had me photograph her wardrobe so he could pick out her dress one night when she and I were meeting some lifestyle friends at a local hip-hop club, and told her she had to wear a temporary Queen if Spades tattoo someone visible and send him pictures from the dance floor to prove it, etc. She was so worked up and compliant we both knew it wouldn't be sustainable, but it was an amazing head trip for both of us at the time. I think she got a real understanding of what it's like to crave instruction from a dominant partner and want to please them, and she absolutely learned what it's like to be distracted by thoughts about sex constantly, the way I've always been. So while she was still strict with me, she was definitely more understanding.
I could go on and on about how crazy hot and intended their next meeting was after all that build up, but that just as long a story as this one and this is already way more than I meant to write. Sorry if you weren't looking for a long-winded story or found this boring, especially after my long response about chastity earlier. I just reread your question and it occurred to me that this one-time experience might be closer to what you were asking about.
TL;DR: Yes, it does sometimes happen that a dominant bull starts playing with the level of power he can exert over a hotwife, including orgasm control/denial. For us, it only happened once, but it was an extremely intense experience while it lasted and helped us grow as a couple.