I'm afraid that idea, while theoretically reasonable, fails when we attempt to apply it practically.

First of all, according to the formula that has been set forth, if person A really wants X, and person B kind of wants something other than X, then person A should get his way. So if Sarah loves Chinese food and really wants to eat Chinese food all the time, but sometimes I would kind of rather have Thai, Sarah should get her way. All the time. After all, she really wants Chinese, and my desire is much milder.

Basically this means that if one person in the relationship has stronger desires, or is more emotional, or even is just plain greedy, that person will get their way all the time.

Secondly, how exactly does one quantify desire? Which of you is comfortable objectively comparing my desire for Thai food to Sarah's desire for Chinese food?

Thirdly, the entire idea relies on the honesty of both parties. I know plenty of people who are so afraid of confrontation (or perhaps who are so hooked on martyrdom) that they will play down their own desires in order to avoid conflict. I also know people who would not hesitate to exaggerate the strength of their desires if they thought that meant that other people would be more likely to concede to their wishes.

And none of that even takes into account unintentional dishonesty or a simple breakdown of communication.

On a final note, even if we ignore the practical difficulties associated with attempting to follow this formula, there is another issue: everyone seems to be treating as axiomatic the premise that the person whose feelings on the matter are genuinely stronger should get his or her way. I'm not saying that I disagree, but I do think that premise should be examined more closely:

Why should the person who feels more strongly about an issue get their way? What precept is that based upon?