For me it's fairly simple.
Descriptive hierarchy ("This is my life partner, Sue, we live together and are raising children and share a primary relationship, and this is my girlfriend, Rhoda, we see each other when we can and share a secondary relationship") that uses terms to describe the shapes different relationships end up taking is perfectly fine and natural, prescriptive hierarchy ("No you can't come to Yule, Rhoda, I don't share holidays with people with whom I'm in a secondary relationship...") that uses terms to limit one type of relationship, often so as to "protect" another ("...because otherwise what would be special about my relationship with Sue?") are problematic.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.