My Boyfriend has DAD issues. 0.0 help?

My boyfriend had a fight with his dad which happened last Christmas. I can't say the story though but the blame is on the dad. The rest of their family also got mad at him but later on they forgave him, except for my boyfriend. One day, his mom told me to talk to my bf about it so that things would be normal again. I tried, many times.. Even before his mom talked to me I already convinced him to forgive his dad and to make things right. But he keeps on saying that it was his dad's fault and that he will never say sorry. There was even a time that my boyfriend got a bit pissed with me for forcing him to make amends with his dad. It's funny that his dad is not apologetic at all even though he knows he was the one who made a mistake. Ego, i guess. It's been 6months since my boyfriend and his dad talked, and i'm really worried about it. Honestly i don't want to intrude since it's family matters but i somehow became a part of it because their mom already asked for my help. I feel pity for their mom because she doesn't know also what else to do.. can anybody give me some advice? thanks..