Will Allah accept the repentance of a sinner who wronged his brother, regretted it, and sought forgiveness, but his brother refused to forgive him?

It is obligatory for someone who has wronged his brother by slandering his honor to seek his forgiveness, and the wronged brother, if he is forgiving, should accept the apology. If the apology is not accepted, then the wrongdoer must increase his good deeds and acts of righteousness, so that he does not become one of the bankrupt on the Day of Judgment, whose good deeds are taken to settle the rights of people. Whoever fulfills what is obligatory upon him and completes the conditions of repentance, Allah accepts his repentance, and Allah may, out of His generosity and love for those who repent, take it upon Himself to satisfy the aggrieved party on his behalf.