約束を破る (やくそくをやぶる) Japanese meaning | KotomoraMeanings
1
expression, godan verb (-ru)
break a promise; go back on one's word; renege
Used when someone fails to keep a promise or commitment. Often implies a breach of trust.
See also: 約束を守る
大事な約束を破ってしまって、本当に申し訳ない。
I'm really sorry for breaking such an important promise.