Should you have rules in your relationship?

I know, it sounds so archaic. Having rules in an adult relationship, but, they are more to safeguard my emotional well being than to police my other half. 

My rules are steadfast and have never changed. I also don't give second chances.

It may sound harsh and I hear you saying "but everyone makes mistakes". 

No, once we start to become serious, I will tell you in no uncertain terms that these are the rules and if you break them, it's over. After ten years of marriage, I can tell you that even now, I would not hesitate to walk.

My rules are simple. 

Don't lie to me. About anything. Not if you were caught watching adult videos on your phone or if you cheated. Always be honest and open. If you are willing to allow me to believe small lies, how can I trust that you will be honest when it comes to the big ones?

Don't cheat, leave. This is a non negotiable rule. We can happily sit and discuss your feelings and reasons for leaving, I will wish you well and probably send you Christmas cards. But, cheat on me and I will take you to the cleaners and wipe you from my memory.

Be kind to everyone and everything. I notice everything from the way you treat an animal to the way to speak to the waiter and I will not tolerate any kind of unkindness or abuse.

Do you have rules? I would love it if you shared them with me!