All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
If this young man is righteous, as you have mentioned, then it is better for you to fulfill your oath and marry him, on the condition that you obtain your father’s consent. If you wish to marry another religious and well-mannered Muslim man rather than this young man, there is no harm in that and you should make the due expiation for breaking your vow by freeing a slave, or feeding ten poor people or clothing them. If you are unable to do any of these, you can fast three days as expiation.
Allaah Knows best.