What is physical cheating? If the relationship exists purely on the physical domain, then you will be greatly offended if you find your partner sleeping around with somebody else, because that was everything that there was to that relationship—the body. The relationship was all about the body, and the body is with somebody else. “I have been cheated! FIR!” 100% of the relationship was about the body, and the body is now somewhere else, so the relationship has been 100% destroyed because 100% of it was about the body.
If you are very offended, absolutely offended when you find someone physically with someone else, then that only means that your relationship itself is absolutely physical.