Is it Islamically permissible for a fiancé to break off his engagement due to his fiancée's stubbornness and disobedience, and is this considered a trivial reason for breaking off an engagement? And what should the girl do in this situation: should she accept the decision or try hard to reverse it?

The general rule regarding divorce is that it is disliked in Islamic law and should only be resorted to after all attempts at reconciliation have failed. However, it is permissible when there is a need, such as a woman's bad character. If your husband wishes to divorce you due to differences in temperaments, there is no sin upon him. You should strive to improve your character and abandon stubbornness, and ask your husband not to rush into divorce. Make clear to him your eagerness and efforts towards reconciliation, and ask him to consider the good aspects of your character, for the Prophet, peace and blessings be upon him, said: "No believing man should hate a believing woman. If he dislikes some of her characteristics, he will be pleased with others." If your husband insists on divorce, then entrust your affair to Allah, for divorce is not always an evil; Allah Almighty says: "But if they separate, Allah will enrich each of them from His abundance."