Is it permissible to break a marriage promise to a girl I do not love, and what is the expiation for that?

A Muslim man is not permitted to correspond with or talk to a woman who is not his wife or a mahram (a close relative whom he can never marry), except out of necessity and to the extent of that need, and within the bounds of propriety and Islamic rulings. If a man wishes to marry a girl, he should propose to her through her legal guardian (wali). It is not permissible to establish relationships or make covenants with her while she is a stranger to him. Your promise to marry her does not necessitate an expiation (kaffarah) if you do not fulfill it, but fulfilling it is religiously required. This requirement becomes more emphasized if the girl rejects another suitor based on your promise.