Within every relationship, there is a delicate balance that exists, sometimes consciously, as within a D/s relationship, and sometimes as an undercurrent that motivates behavior, decision making, and how we interact with each other, and within ourselves. There is an (often unspoken) expectation that certain relationships will be a higher or lower priority than others, that some will have official status, as with a marriage, while others will be emotionally important, but not often publicly acknowledged. Some people have an idea that all relationships will be equally weighted, that "fairness" or "equality" are qualities to strive towards. Some of us want a say in the lives and decisions that our partners make, while others view that as controlling and undesirable. Is balance achievable? Is it desirable?
For me, people that are more entwined in my life, those that give of themselves and make my life function well, have a higher priority, more input. Their opinions and requests are given more weight as I consider decisions. I share a higher degree of information, and put more effort into communication. It's probably a reflection of my practical side that I do things this way. It seems eminently "fair" to me that someone who helps me out on a day in and out basis would have more input than someone I date occasionally, even if they are similarly emotionally important.
Equality is a fiction. Within our relationships there is a spectrum of feeling, thought, obligation, action, sexuality, desire, drive, intellect, responsibility, intimacy and much more. Each individual that we connect with is going to inspire a different blend of these qualities. There is no possible way to make relationships equal, particularly since they often grow based on shared experience that is unique to those present. Even with people present in the same space and time, the same event will hold different significance, emotional resonance, and touch them in unique ways. How could there ever be an expectation that someone should feel the same way about different people?
Fair and equal are traps. Any parent that has handed multiple children an identical treat, only to have one insist that the other child has somehow gotten the better choice, would recognize that even when things are precisely equivalent on paper, it's in our nature to wonder if someone is getting it better than we are. For me, the key thought is more related to balance. I cannot make things equal or fair, but I can try to give to each person as much of what they need from me as I have to give. Sometimes what I have to give is limited by other circumstances, like time needed to work, or by other relationships, including familial ones, or by the specific need of a particular partner.
Prioritizing is part of life. If we weren't capable of prioritizing, we'd collapse under the weight of all the choices and options available to us. So why is there so much resistance to prioritizing our relationships? Within the framework of a mono relationship, there isn't as much of a chance that someone will feel "less than" another person, or if that happens, it's a different type of connection, like one with a family member or friend, and we can more easily recognize that difference. Within a poly framework, we are having romantic relationships with more than one person. It's harder to make those differences feel obvious, and that is why we have a tendency to try for the equal and fair model, and why prioritizing can feel like making a better/less than choice, versus giving what is available to each individual based on the unique relationship that is shared.