Will a girl's wish to have the person she admires as her future husband come true, despite him not reciprocating the same feeling, and will her continuous supplication for him to be her destiny be answered, knowing that the spouse is predetermined from birth?

Thinking about divine decree (qadar) is futile. What is required of a Muslim is to exert effort and leave the matter to Allah. It cannot be definitively asserted that your marriage to this young man is good for you. Therefore, ask Allah to make him your husband if there is good in it for you, and be content with what Allah has decreed, in accordance with His saying, the Almighty: "But perhaps you hate a thing and it is good for you; and perhaps you love a thing and it is bad for you. And Allah Knows, while you know not." There is no harm in offering yourself to him for marriage within the Islamic guidelines. If he does not show interest, do not pursue him. What Allah has decreed in the Preserved Tablet (Al-Lawh Al-Mahfuz) does not change, but what is in the hands of the guardian angels (hafaza) may change.