In halacha, agreements made regarding a wedding are very serious. Much more so when tnnaim are performed. Breaking off the wedding is very serious and has financial ramifications. I know a rav who has said that if the situations comes up where they want to break it off, better that they should get married and divorced right away rather than breaking off the engagement, considering the complexity of the financials and making sure the right people get what they are supposed to, along with some sort of a bad omen.. I don't think I agree with that, as the financials can be worked out in beis din if necessary and taken care of like any financial dispute, whereas a get will disallow her from marrying a kohein along with making it much more difficult for her to find a mate considering her status as a divorcee, but I mention it just to show how complex it can be to break off an engagement.

In Haifa, a young Haredi couple got engaged after a short courting period. As they prepared for the wedding, somehow they signed an agreement to split the costs of the wedding. Somehow, she signed the agreement, laying out an initial 10,000NIS, and he got away without signing saying he would do so at a later time and would give his portion a bit later.

After a bit, as they were preparing for the wedding, after they met with the band, he changed his attitude and then broke off the engagement.

She is suing him now in small claims court for 30,000 NIS for a combination of the money she laid out that she has to take a loss on (in part), along with the trouble, trauma and stigma she will now be suffering.

In his defense, he claims that when he came to Israel he was stricken with the Jerusalem Syndrome, which basically makes people a little crazy, often they move to more religious extremes, at times even to the extreme point of the person thinking he is the mashiach. He claims his suffering from Jerusalem Syndrome is what made him propose marriage to her, but he later realized that she is not as she had presented herself, neither as educated nor as healthy, and he felt he had to break it off. He claims he discussed his doubts with her, asking her to hold off preparations so as not to incur any additional expenses, and she continued anyway taking on the expenses on her own volition.

The judge decided in her favor, saying that his claims of her misrepresenting herself have no foundation and he was aware of her true situation before he proposed. The court awarded her about 18,000 NIS, covering court costs, financial loss, and a bit for her trouble. The decision says nothing about Jerusalem Syndrome being a factor.