Help, My Manhood Is Too Small and I Think My Wife Will Cheat On Me

Please, I need your help.
The problem is that my manhood is too small and I am afraid my wife will cheat on me because of that. She doesn’t complain of sexual dissatisfaction but I can see her eyes each time we make love. I know she doesn’t enjoy it.
Please, help me. How can I make her enjoy having sex with me?