I have had three years to reflect on this subject while on my own and have concluded that a truly healthy relationship is close to an impossibility. There will always be one partner unhappy with some aspect in the other; there is always something they could do better.
The level of commitment between them is also unfortunately unbalanced.
The absence of a desire to want to change the other is what is required. We need to accept their essential nature while still being able to advise them as we accept their counsel as well.
Human nature is bizarre and fickle and most of the time we are insecure about ourselves as well as our role within a union. Many of us are also afraid to be alone and so we settle for something less than we deserve.