It's a long shot, because I'm guessing she was keeping it a secret and you found out by chance, but marriage counselors aren't just for married people. My bio father and mother saw one after they broke up to better themselves, learn how to get along amicably, and to be better parents to me, especially now that they were single. My mom and step dad saw one too while, and after, they were going through their divorce for the exact same reasons, as well as to deal with anger and resentment issues. Sometimes exes see them to learn how to better communicate and interact with each other. I really hope this is the case, but she still shouldn't have hid it, makes her seem guilty if something more.