The person denied an explanation must build a life around somebody else’s unexplained decision.

Refusals without reasons are especially hard to live around. When you know why, you can adjust, appeal, or accept it. When you do not, you have to arrange your plans, finances, and hopes around a blank, and part of your attention stays permanently on a question that cannot be closed. The absence of an explanation is not neutral, it transfers work onto the person who lost.

Ask for the reasoning in writing, once, plainly, even when you expect nothing. If you cannot get it, try to decide what you will do in each of the likely cases so the unknown stops governing everything. And if you are ever the one deciding, give the reason even when you are not required to.