Cheating is a character issue. The very traits that allow someone to cheat are the same traits that make them a poor choice and bad risk as a partner or friend. Lack of integrity, decency, and honor. Poor boundaries. Poor impulse control. Lack of regard for the well-being of people close to them. Selfishness. Self-indulgence. Entitlement. Those are the ingredients of a cheater. Those are also the ingredients of someone with poor character. Not someone you’d want as a partner or friend.
If someone can betray their partner, they sure as heck have no loyalty to mere friends. Choose the company you keep very carefully.