I'm looking for a word that describes that state of being-free-of-power.
"Powerlessness" is not it, as it describes an unwanted state of being deprived of power.
The state I'm wanting to describe is that in which one is not even in need of power (free of the need to wield-power-over or give-power-to others; neither authoritarian nor submissive).
Sentence example: Peter is ___; he has no authoritarian control over his wife as he is secure enough to not seek power over others; nor does he give others any power over him. Peter and his wife live under free association, with neither party seeking to influence (seek power over) the other, and as such they experience a life full of delight devoid of the common relationship pitfalls.