Futa Ophelia was (initially) apologetic that she just couldn't control her urges. And Ophelia didn't necessarily want to take the women away from Sterling, they just ending up preferring her larger dick and her miraculously addictive cum.
By contrast, Brenna has a mean streak, so I could see futa Brenna taking more enjoyment in purposely tormenting Sterling and the girls. Maybe Brenna makes the girls fuck Sterling after getting addicted to her, and they say how he can't satisfy them anymore. Then Brenna fucks the girls again, while making him watch as they tell him how they prefer Brenna. All while streaming on her porn channel.
Yeah I could totally see that happens and Brenna would probably try to justify herself saying that it's just for the channel. Brenna is more honest with herself so she would not be restraining herself at the beginning and such situation would make total sense.
Bur truth to be told, when it comes to Ophelia INITIALLY she wasn't into tormenting the men around... but when she accepted her new nature, I think the way she acts is not the simple "cannot resist the urge".
In fact, she start to be a bit sadistic or at least is teasing about it, heck when Sterling complains that Mallory does not want to have sex with him anymore and he ask her if she did, she answers him with a devious smile that "had... just had... will be having".
Even at first she was taking pleasure in taking girls away from him, she just did not admitted it to herself because they were not the "main" one. And once she decides to go outside and seduce girls from other games, she is nearly openly sadistic about it.
When she is taking Max mother, she kind of has a smile on her face and tells him that she has a "soft spot" for men who "dreams big" and to say hello to his grandmother because she is the "mommy's mother"...
She is also similarly a bit devious in asking Melinda to order her son to polish the silverware while she is impregnating her. Or ask the girl from BEING A DICK to name their firstborn after the MC.
It's very clear that after a while, Ophelia has become a sadistic predator that loves NTR