As far as I'm concearned I whole heartedly agree with this, but I would like to add one more thing. My ex-wife would consider it cheating if I would discuss our sex life in any way and in any form when she wasn't present. Even on an anonymous forum like this. Even though I thought she was a bit too touchy about it, I did respect her wishes. My point is that it's not really relevant what can be considered cheating by most people. The only thing that carries any weight is what your partner judges as cheating, no matter if your conscience is intact.
For me cheating is not an option. If I need to cheat, I also need to break up with her.