Often in relationships things do not come down to "better" or "worse" decisions, but rather whose preferences count.

Well said.

Life is about choices and preferences, not problems and solutions, but most people are so accustomed to rationalizing everything, and so mesmerized by language, that they think these choices are determined by logical analysis. And it is precisely in a situation of such conceptual confusion that the person with greater verbal agility has the greatest advantage, though as you add, the will to power and the determination to fight for it matters too.

Decius wrote:

Is it abusive to be smarter and to make better decisions and to have those decisions implemented because they are better?

Better, by whose values? And what makes you believe that the "better" decisions routinely win in joint decisions in a committed relationship? The excellence of the solution wins out over the dominance hierarchy? Not likely.