Many misconceptions & false choices:
First off the only relationship / marriage worth having is the one where both parties are actively choosing to keep it.
Second a person only "controls" you as far as your consent, i.e. one spouse controls the other only to the degree to which they consent to be controlled.
Sexually speaking: An individual in a marriage needs to (1) make their partner's needs a priority and (2) make their own needs a priority.
If you make your partner's needs and your own needs a priorty, very rarely will either of you not get to an acceptable negotiation. Regardless if you are into power exchange relationship or egalitarian 50/50.
BOTH people make that their commitment there will be no issues. Not one.
If you want a dog part of the deal is to feed it & walk it. Even when you don't want to & even when it's "not satisfying".
Even if the wife has a gaping, perma-stretched out vag and she needs Shane Disel with a Bad Dragon girth extender just to orgasm & the husband has a mouse dick & cums in two pumps, if he wants to (try) & fuck her occasionally there's no reason that should be off the table.
They should be able to negotiate a suitable agreement between each other before taking into consideration any Bull or 3rd.
Likewise if the hubs wants denial & the wife doesn't there should be a win-win agreement there somewhere.
I've met seen some really hardcore couples who regularly "take time off" just to reset and rekindle their intimacy.
The kink is always waiting when they want to come back to it.
I'd say the first mistake couples make for dipping their toe in denial or exclusivity outside the marriage is they don't put an expiration date on it to reset & reevaluate.
Wife wants exclusivity with Bull? Great, predefine what exclusivity means. Then try if for a month. One. Month.
Define everyone's role, define EVERYONE'S needs and how those needs will be met FOR THAT MONTH.
When the month is over, its over, even if everything is going great, all kink pauses.
Pre-exclusive sex life resumes between couple, reset and ******* yourselves to take a week or two to "unpack" the experience.
I heard a Domme in a neighboring State say of her caged, cuck husband: "If he's a good man he's going to want to make sure my needs are met. If I'm a good woman I'm going to recognize that effort want to make sure ALL HIS NEEDS ARE MET."(Emph added).
Kinda simple as that.