“Open marriage”

I met someone through an app. I always ask potential playmates if they are single, dating, married, open, etc. This particular man told me he was married, it was open, and they play separately. He said all the right things that I have learned and read like their “rules and boundaries” for his marriage and being open. This man invited me to go out of town on multiple occasions for “group play”. I always turned these offers down, and I was looking for something much more casual. We ended up meeting on several occasions, always in my home, and always during the week/daytime. Long story short, his wife reached out to me after finding our messages through the app to tell me they are not open, and have never discussed this. 12 years together. Two children together. I’m new here. How do I trust men who say they are open? How was I suppose to know this when he said all the right things, and told me about previous interactions with other women? Do I need to have a conversation with the wife or gf and insist on this? Thanks for the input. I wasn’t emotionally attached to this man but I obviously felt horrible for his wife.

*for context, this was removed from a poly page and asked to post to a different page. *I’m new to the communities of “non-monogamy and “poly”