What to do if a boy promises for marriages but doesn't marry

Hi lawyers, i need your help desperately, this is regarding my daughters marriage she is in love with a guy even he is in love , everything was fine, they were supposed to come and meet my family for further discussion on marriage but all of a sudden the guys mother said no to this marriage and has changed the guys mind also by emotional blackmail, in the meantime my relatives all know that my daughter likes someone and will be getting married to that guy only but recent events in the guys family has left my daughter devastated, the guy is not ready for register marriage also because of his mom, now she is finding a gal for him in their relatives both of us are Christians i am worried about my daughters future i don't no what will happen, as per law what can be done to make sure this guy gets married to my daughter i cannot find another guy also because everyone in my relatives knows about this, please help, thank you very much.