At what point is a compromise in a relationship irrational?

Couples can reach a point where one of them wants something that is mutually exclusive from what the other wants (To move, to have children, to do something sexually), and it becomes a make-or-break moment: either the curtains go, or I do. So to speak. But when is a spouse's refusal to accept a change irrational? At what point is it no longer something one must learn to deal with, but instead must break up with the other person over? And if it hasn't yet crossed over into the break-up point, how can one reach a suitable compromise, when the choices are, or seem, mutually exclusive?