To break a promise is to fail to do the thing you swore you would. The birthday you said you would be home for, and were not.
Promises break; they do not fall or fail, and no other verb sounds like English here. It takes to about the person: he broke a promise to his daughter. Break and keep are the fixed pair, and neither verb transfers: you break a rule and a record, but you keep neither of them the way you keep your word.
1phrasebreak a promiseTo fail to do what you swore you would do.
“It is a hard thing to break a promise to a child.”
break a promise is a failure to do what you said.
Practised in Common Word Pairs