Breaking a promise.
It is attached to lying and deceiving.
I think this is one weakness we as human should pay attention to.
Please discuss and post what you can find since I know there will be many guidelines in Islam prohibiting it.
Now, forgetting to fulfill a deed is not so bad. One must try to make a note to himself or herself so the person should not forget.
Other point is, if a promise is made for something not halal or jaayiz then one has no obligation to fulfill.
All I would think is to make it clear to other party the intention and why not able to fulfill the promise.
That will serve two purpose:
1- The promise will not fall in to deceiving.
2- Other person could learn something good, why a ‘bad promise’ is not carried out by a conscientious person.
If one thinks other person may take it wrong or will not understand, then one may just stay quiet and still does not fulfill the promise.