Before deciding to be in a relationship I think both parties should get to a level where they are absolutely open to each another, e.g Trust, being a major talking point here. However, if such conditions aren't met - where one side can be free to express/befriend the opposite gender without any attractions or whatever, I don't see why such a relationship should continue.
It all boils down to respect, and trust IMO. Without it the foundation for any relationship is bound to collapse.
RE: The Mentality of control in relationships!