It's expected that people should keep their promises.
Fred is married and is taking a vacation with his wife.
Fred wants to save money.
Fred promised his wife they will go to Paris on vacation he finds a vacation planner to save some money and book the Paris vacation.
Fred promised his wife he will take her to Paris but Fred finds a cheaper vacation and books that instead, so he saves some money.
Fred and his wife have a amazing time on vacation in Paris.
Fred and his wife have a awful time on vacation and Fred wife is not happy.