You have tried the right solutions but it may take more time than you have given it. You are trying to be a good partner so that is a plus. Communication is your only real method. His accusations could be a sign of his own insecurity. That means he has to work on him. He manifests this by blaming you. Reassurance after while usually helps to minimize this. He begins at some point to realize that he has a partner mate who genuinely cares, Time has a way of solidifying the fact that you are innocent. The other possibility is that he misinterprets your behavior and twists it into this belief that you are unfaithful. You can't convince him of anything until he is ready. Over time he should become less willing to believe these misconceptions. Take notice of your behavior so that you don't reinforce something that isn't happening. Keep your focus on him until he can believe that your intentions are honest. All in all try to move him slowly to a place where he is not suspicious.
Please press accept; this is the only way I am compensated