People make promises all of the time, of which, some promises are of such a serious nature, that because a verbal agreement can be legally binding that the party that believes that the promised has been breached, has the right to sue the offending party. In the case of a breach of promise, the substance of this is actually the promise of marriage, in which the fiancé that gets cold feet or decides that they do not wish to get marry after all, or was deceptive in their desire of marriage, of which, all of these, are subject to and are known as the breach of contract to marry. It is important to realize, that historically women did not have the income opportunities as well as educational opportunities that they are so provided with today, so that, an actual promise of marriage, was a serious commitment meant to indicate that the man making the promise would be taking care of his wife-to-be for life. So too, this meant as a matter of course, that the bride-to-be would quite obviously no longer be considered as single and thereby available, but rather would be clearly seen as committed and therefore unavailable. In addition, since both parties would have made a binding commitment to one another, the woman would be somewhat vulnerable to relaxing her sexual mores with her husband-to-be.
Nowadays, a breach of promise, in regards to marriage, is no longer considered a legal offense, at least in most States, or with States, which still have this statute on its books that this is seldom enforced or taken seriously. This does mean, in effect, that those asking for a woman's hand in marriage, can simply walk away from that commitment, at any time, even on the day of the nuptials, itself, with little or no legal liability. However, there are some States that are still enforcing the statute, of which a woman can actually still sue for breach of promise to marry.
The fact that this statute has fallen out of favor, reflects that the law no longer sees a promise of marriage as a legally binding contract, probably because the law does not have a compelling interest to intervene into personal relationship commitments between two adults; in addition to the fact, that many States have no fault divorces, which basically allows either party to walk away from matrimony, for no reason, at all, other than that being their prerogative to do so.
All of the above basically means that a man's word when it comes to marriage proposals is something that in today's world, is apparently retractable, and at the man's volition. All of this signifies that the institution and the formalities of marriage, is far less secure today than it was back in the day. To a certain extent that is quite unfortunate, of which, there appears to be a high correlation that with the appreciably higher degree of freedom, suffrage, and opportunity that women now have, that the less secure and protected marriage proposals and marriages have become; of which the male rascals that mouth promises but don't commit to them, don't seem to mind this much at all.