Will God accept the fasting and worship of one who harbors malice towards a person who wronged them, and has not forgiven them after entrusting their affair to God?

The fact that the questioner does not harbor malice or hatred is a praiseworthy quality. What the man did by not fulfilling his obligation is not from the morals of the people of faith. The questioner's feeling of animosity towards him does not prevent the acceptance of his deeds and has no bearing on the validity of his fasting. The existence of malice and hatred towards an oppressor is a natural human inclination. The حديث (Prophetic tradition) about the gates of Paradise being closed due to animosity is understood to refer to disputes rooted in falsehood. As for the forbidden abandonment exceeding three days, it is resolved by extending greetings of peace. Regarding a woman's relationship with a non-mahram man, it must be regulated by the controls of the Sharia.