I believe that my wife was with someone this morning other than her husband, namely me?

My money says that her friend will cover for her. If I were you, I check her panties for any evidence that could of been left behind depending on how cautious she was. Even if she did use protection, there might be extra secretions left behind by her being so turned on. You might want to follow her next time, or hire a private detective. But none the less, check her panties under a black light.