A guy is letting me fuck his wife for 2 days is it too good to be true and how should I limit my risk?

I met this couple on a dating app and they had said they were wanting a younger guy to cum into his wife. He wanted to watch a little but told me I had full access to her and her friends might stop by. They said he can’t get her pregnant and young fucking her raw gets her off. This will be in a couple days this feel a little too good to be true like almost like it could be a setup but everything they have said has added up and showed me proof of them doing this before I want to do it bc it will fulfill all my sex fantasies but I don’t know these people. I want to atleast attempt but what precautions can I do to limit the risk?