I understand what you're saying, but I thought, by way of explanation, that I'd mention that my poly relationship doesn't subscribe to primary, secondary either. My bf's other gf is by no means "secondary". She is just going in a different direction in life than my bf. She is Christian and one day wants to settle down and get married. If my bf wasn't poly, and was interested in marriage, I'm sure she'd want to marry him. But since she has an opposite agenda in life, their relationship seems to have a pre-set time limit of some sort. Regardless, they are very much in love and see one another almost every day and have a very sweet and committed relationship. Same with my other partner. He is not a step below my first bf, just different in almost every way, but both of these relationships have the potential to last a lifetime (as much as any mono marriage or long term relationships does).
The term "secondary" has always creeped me out. And I don't think I engage in the kind of relationships that fall neatly into those categories/hierarchies. Thanks for your input. I often enjoy reading your posts