Compare the consequence each partner cares about
Write each option in the same terms. For train A, a lower fare might mean arriving at eight and eating after the family dinner. Train B costs more but reaches the host at five. Ask each partner what they would give up under each choice. The traveler who values a calm arrival can then explain the actual consequence rather than simply saying the expensive option is better.
Look for a third option that preserves both priorities
Compare each option against the two stated needs. If the cheapest train arrives too late, look for a middle option or agree which need takes priority on this occasion. Do not treat a low price as the whole answer when the actual disagreement concerns time together.
Record which priority decided this occasion
Maybe the host offers a later dinner, or a midmorning train at a different station meets the budget. Check the extra journey before treating that as a solution. If no third option works, agree which consideration takes priority for this trip and why. Write down who books and the latest acceptable price. Choosing the quicker train for this visit does not establish a permanent household rule that convenience always outweighs cost.