If I possessed a magical powder that I could dust upon the heads of every well-intended couple seeking a closer, more harmonious, satisfying relationship, what sorcery would those particles spin?

Two things:  they would first give each person the ability to live by the creed of two equally-valid, subjective realities.  Secondly, they would impart the capability to catch oneself when physically flooded; to disengage, and – once calm – to eventually return  and engage in effective dialogue.