Again, there's the trouble actually measuring feelings, but why shouldn't the person with a smaller emotional stake in the situation acquiesce?

The answer to me seems obvious: a smaller emotional stake does not mean that there is no emotional stake.

Essentially what is being suggested here is a utilitarian philosophy in which the greater good must prevail; one person's unhappiness with a situation is acceptable provided that it is outweighed by another person's happiness with the situation.

I prefer to approach these situations from the perspective that suffering is unacceptable rather than the lesser suffering is acceptable. This seems to promote a less linear, "either/or" perspective and encourages an attempt to find innovative ways to keep both people happy.

Unfortunately, this is a hard philosophy to adhere to, and it only functions when both parties are attempting to follow its precepts... which is an admittedly rare occurrence.