Definitions of breach of promise
a complaint that someone has not done what they had promised to do, but which may not have been made in the form of a contract
Palmer wants to sue party defectors Glenn Lazarus and Jacqui Lambie for breach of promise.
a complaint that someone, especially an engaged man (=fiancee), has decided not to marry a person sometime after having made a marriage proposal to that person that was accepted. In some jurisdictions, this either is or was either a civil wrong or a criminal offence.
Defendant argues that the common law action for a breach of promise of marriage should be abolished by this court.