Oh, well really there's nothing that you can do about your partner, and vice versa there is nothing that they can do to ensure that you don't cheat. Power comes into play when it comes down to who feels like they can get away with what in a relationship. 
there is  NO RELATIONSHIP  in such circumstances., it is just blackmailing  with  ..emotional.. financial ..physical violence ...etc..etc..  
So for example, if one is self-sufficient and the other dependent then the self-sufficient one will feel like they can get away with more. But that's only one form of power. Sexual capital is another form, in this context the ability of one or the other party to easily replace their partner with someone of greater or equal perceived value.
Hmmm......Yes.. if women  become self-sufficient  then the self-sufficient one will   get away.,  that is a good reason,   why allah doll gives all powers to men to control women ., 
So yeah, it's very complicated. And some people just like taking risks and/or are callous, and other people are risk averse and/or doormats so really there's a wide variety of reasons that people do or don't cheat. If it's important to you, I'm sure there's ways to end up in such a relationship.
Nope it is very simple  .
." do not fall for blackmail  and do not use  blackmail  to control others  "  ...............another form of golden rule............