It can be important to go back from time to time and reexamine the rules that you've set, although that's something much harder to do after they've been broken.
For Tonberry and myself, I try to remember the frame of mind that I was in when I proposed or agreed to any rule. When I was a lot more apprehensive than I was now, the rules we set early on were a lot stricter, and I would at this point in my life I wouldn't agree to any of them, even as the partner without a second relationship.
If the rules were broken, it's good to take a look at why they were broken and why they didn't work out. What sounds like it might work in theory doesn't always work in practice.
To use Tonberry and I as an example, she did *technically* break a rule we set when she entered into a relationship with Sean, because she didn't tell me the two of them were going to be in a relationship. I found out by accident that she was seeing someone, although I guessed who it was almost instantly. The rule about talking first and dating after just didn't work for us, because Tonberry and I are both the type of form a friendship first and then fall in love, and the evolution isn't always obvious.
My advice, to reiterate, would be to try and understand how and why any breach of the rules happened. It may sound like rationalization at first, but in the long run it may lead to a happier, more natural relationship.