The best way to find out if your wife is cheating on you is to ask her! If you know her well enough to figure out if she’s lying to you or not, then you’ll have your answer with hers.
If you can’t tell if she’s being honest with you, then keeping extra alert to her behavior will help you figure out what’s going on. It’s hard to answer further without knowing what it is about your wife’s behavior that makes you suspect infidelity.
Let me know more about your situation, and I’d love to help you! 🙂