I am married, but how to avoid marriage robbery?

I think this is inevitable, so it is better to find a way to solve it. For example, what factors? You should be prepared. For example, when my husband went to tell the baby's fortune and named him, the fortune teller told him that we were getting a divorce. At that time, he came back and said that the fortune teller was a liar. Now, he is having an affair. For the sake of baby's face, I forgave him many times, but now I just want to understand that I don't trust him very much. Actually, I live a marriage without trust.