How would you reach out to him?

My SO is the sweetiest, caring, smart, driven man that I have ever met. He respects me, he is very attentive and affectionate, he listens to me, he's there for me in every way. I am so incredibly lucky to have him in my life. His father passed away when he was young and his mother fell into alcohol and drugs so she wasn't there for him. She went from one man to the next moving him and his sister all around. When he was younger she would come home messed up and would touch him. When we first started dating I told him some things that had happened to me and he had hinted that he had something similar happen to him. He eventually told me what had happened and that he didn't want to speak about it again. So I have respected his request. But I know that weighs heavy on him at time because sometimes he has some intimacy issues. I don't want to bring it up and upset him but I don't like to see him hurt like that. It is something that he will have to eventually have to work through. But I don't know what to do, any suggestions?