All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
There are some Ahadeeth which indicate that Allah forgives the sins of His Creation on the night of the middle of Sha'baan, except for the polytheists and the two Muslims who have malice against each other.
For more benefit, please refer to Fatwa 88046. Also since you write to us in Arabic at time, we refer you to the following Fatwa in the Arabic site 262837.
This is regarding forgiveness. As for not accepting one’s good deeds, then we have not come across a Hadeeth that indicates deeds are not accepted from those who have dissension against each other. As far as we know, there is nothing about this in relation to the month of Ramadan.
Allah knows best.