Breach of promise is a common law tort, abolished in many jurisdictions. It was also called breach of contract to marry, and the remedy awarded was known as heart balm.
From at least the Middle Ages until the early 20th century, a man's promise of engagement to marry a woman was considered, in many jurisdictions, a legally binding contract. If the man were to subsequently change his mind, he would be said to be in "breach" of this promise and subject to litigation for damages.
The converse of this was seldom true; the concept that "it's a woman's prerogative to change her mind" had at least some basis in law (though a woman might pay a high social price for exercising this privilege, as explained below)—and unless an actual dowry of money or property had changed hands or the woman could be shown to have become engaged to a man only to be able to use large amounts of his money, a man was only rarely able to recover in a "breach of promise" suit against a woman, were he even allowed to file one.
Changing social attitudes toward morals have led to the decline of this sort of action. Most jurisdictions, at least in the English-speaking, common law world, have become increasingly reluctant to intervene in cases of personal relationships not involving the welfare of children or actual violence. Many have repealed all laws regarding such eventualities; whereas in others the statute allowing such an action may technically remain on the books but the action has become very rare and unlikely to be pursued with any probability of success. What is arising in its stead are judicial opinions and/or statutes permitting a breach of contract action for wedding expenses incurred when the nuptials are called off, or for loss of employment, moving and living expenses incurred by one party as a result of an engagement which is later broken.