A promise is defined as any agreement that yields an obligation
It is acceptable not to keep one' s promise if either the person to whom the promise is made tells the promisor not to keep it, or the promisor is unable to fulfill the obligation due to circumstances beyond the promisor' s control
Felicia agreed to tutor Alan in mathematics on Tuesday. However, on his way to the tutorial session, Alan was injured in a car accident and was unable to attend that day. Thus, it was acceptable for Felicia not to tutor Alan in mathematics on Tuesday.