How can repentance be completed and accepted while the girl who was wronged has not been forgiven, and is marrying her considered a solution to fulfill her right?

You must supplicate profusely for the girl, asking for her guidance, repentance, and forgiveness, along with frequent seeking of forgiveness for yourself, regretting what you did, and resolving not to return to it. Your obligation towards her will be lifted by the blessing of your repentance. Marriage to her is not a condition for repentance. However, if she also repents and regrets, there is no objection to you marrying her, thereby protecting yourself and her from sin. If you decide to leave her, we advise you to change your contact information.