Force majeure, and where a delayed flight sits
Events outside both sides' control that make the evening impossible, such as a transport shutdown or an official instruction; the deposit becomes credit.
Occasionally an evening is stopped by something neither side could have prevented. The terms treat that case differently from an ordinary cancellation: nothing is forfeited, and the deposit becomes credit held against a later date.
What counts
Events that stop the booking for both sides at once. A transport shutdown in the city. A serious disruption that makes the journey impossible. An official instruction that prevents the evening going ahead. In each case, the booking could not have been kept by anyone, and the deposit is held as credit for a date you do not have to choose immediately.
What does not count
This is the part a traveller needs to know before paying. A flight delayed or cancelled by an airline is not force majeure, because it stops only the guest and the evening in Amsterdam could otherwise have gone ahead. The same is true of a cold, a change of plan, a meeting that overran, a missed train or a decision to stay in. Each of those is a move or a cancellation on the guest's side, read on the ordinary scale.
Why the line is drawn there
An evening booked from abroad is exposed to many things the guest cannot control, and if all of them counted as force majeure, the deposit would protect nothing. Drawing the line at events that stop both sides keeps the rule honest and predictable. It also means a traveller can protect himself: an evening placed away from arrival night, and the twenty-four hour line watched for doubt, keeps airlines out of the question.
When the house is the side that cannot perform
That is a separate case, and it is not force majeure. If the house cannot perform the booking, or the woman you named cannot come and you do not want to name another, the choice is yours: the deposit back in full, or held as credit. The booking terms page sets out both cases, and the journal note on airline changes deals with the flight question in detail.