Is it considered an injustice to a girl if the young man's father withdraws his consent to her marriage after being convinced, and then marries the young man to someone else, causing her sadness and distress?

It is permissible to withdraw from an engagement for a valid reason, and it is disliked without justification. Do not grieve over the loss of this suitor, nor be saddened, for all that has occurred is by Allah's decree and wisdom. Allah may avert something from you and reserve something better for you, for He knows best what benefits His servant and is more merciful to him. Allah Almighty said: (And it may be that you dislike a thing while it is good for you, and it may be that you love a thing while it is evil for you. And Allah knows while you know not.)