Usually, promises put the person to whom they were given into a certain dependence. Person make plans and associate hopes with it. Therefore, in cases where a person does not keep his word, he does not only demonstrate his irresponsibility but also a level of disrespect.
If you cannot fulfill your promise or keep your word, always talk, explain yourself and apologize. After all, the most important thing in any relationship is honesty and humanity.
Natalia Turanova-Cengiz 