Dominatrix steals an enemy's husband
This story idea could work just as well with the genders flipped and a dominant man stealing an alpha male's slut wife and ruining him in the process, but somehow I pictured it with two women fighting over a submissive man.
But as I picture it, here's how it goes: An alpha woman, a powerful but fairly young (mid-30s or so) marries a much younger man (anywhere from 18-24.) He's pretty much lazy and shiftless, doesn't have a job, and is just there to look good; she loves showing off her trophy husband at parties and work functions, and he loves being taken care of.
She's ruthless at work, however, and has drawn the hatred of many, especially an underling who aspires to move up in the same fashion as she has. The challenger is younger, say, late-20s, also ruthless, and wants everything the wife has.
The wife parades her husband around at a party, dressing him as minimally as possible (maybe it's an all-female-run company where all the men are young trophy husbands and only wear underwear) where the challenger steps in and sees how easily the husband can be dominated. With a little convincing, she sneaks him into a secluded area and fucks him, introducing some domination elements.
Soon he's visiting her at work and she's turning their sessions into full-on BDSM, and he finds himself explaining mysterious bruises to his wife. The wife, too concerned with her career, buys his explanations, and she totally ignores his desires to be dominated. Meanwhile, the challenger gets more bold with her domination of the husband, even coming to the wife's home to "Curry favor."
Soon the domination becomes complete and total, and the husband becomes his lover's agent in sabotaging his own wife. The wife slowly loses her grip, and the challenger seeks to take over her position - "saving the day" after the wife "screws up." Meanwhile, the husband starts to make his domination more apparent, even calling his wife by the wrong woman's name in bed.
Finally, the husband files for divorce, taking most of his wife's things, and the challenger gets the wife fired, leaving her ruined. He marries the dominatrix and goes back to being a submissive trophy husband, enjoying his freakish dominatrix of a wife.
In the last scene, however, the husband ends up chatting with a woman who's even more twisted than his new wife...and more dominant. Predictably, she fucks him senseless, and the story starts over.