How do u better communicate with a significant other that has in their past life spent over 20 years in prison?

Twenty years is a long time. The key to communication is trust. Trust is earned over time. We are not suggesting that there isn't any between you; we are saying that you two need time together to learn to trust. When a man is incarcerated for twenty years, he is used to be told what to do, when to do it and there isn't much room for independence and freedom. So, they become introverted and good at keeping their emotions in check so as never to appear weak or vulnerable. You are probably experiencing a little of all of this. If the relationship is given some time to mature, and you are patient things should work out in the end.