For something to be special it has to have a value that is different to the value of something else. We give it its value by taking away value from something else.
So if I have an apple and an orange, which are essentially equal, and I say, well, I like apples more than oranges, I have to 'demote' the orange and withdraw some of its value and give it to the apple. Now I have a sense that the apple is more important or 'special' than the orange.
What this does, is it makes me have a 'special love' relationship with the apple, and a 'special hate' relationship with the orange. I've also turned the apple into an idol, and the orange into an enemy.
The Course also talks about how we use special love to cover up special hate. The ego has made a world from separation and has made everything in the world be separate. This is based on hate. It is an attack on God. However, the ego then comes along and tries to 'cover up' and deny this hate by creating the illusion that things are somehow joined. It does this by the illusion of 'sameness', things being similar, of like mind, or having minimal conflict.
Minimally conflicting individuals end up as 'friends and allies'. And as the Course says, these allegiances are formed because two people temporarily agree to be against something else. Thus their allegiance still 'includes' an idea of attack and rejection, because it can't exist unless 'everyone else' is not like them. Thus the friends become special and have a special love relationship. But this special love is at best temporary, and covers up the foundation of the relationship which is hate. Separation from others. Isolation. Exclusivity. And so if something takes away that veneer of special love, it 'reveals' the hate beneath it and the claws come out.
While we attempt to make certain parts of the world more important or valuable than others, we make them special. This is our attempt to 'spiritualize' the dream. We attempt to make some parts more spiritual than others, so that at least some of the parts seem sacred, spiritual, holy, valuable, rather than it all being equal and neutral. In this way the ego holds onto these parts of the dream to make it real and to be attracted to it. And of course, to be attracted to one part of the dream requires the formation of a 'shadow' attitude which is against other parts.
So for example, to me, Apple Mac computers are more special than Windows PC's. Green grass is more special than brown. Summer days are more special than winter. Certain TV shows are more special than others. The olympics are more special than regular team sports. And raspberry-anything is more special than most other flavors. These are things I've made special, at the expense of other things being despised and disliked.
This is where the Holy Relationship comes in. With a goal of true holiness, we recognize that instead of depending on another separate thing to 'get' what we lack, or to reinforce our own self-specialness, we instead become wholly dependent on God. It is now God who created us, not our parents. God now also created our children, and he is responsible for them, not us. This of course dissolves all family structures. Absolute equality is the only family - God's family. Equality dissolves specialness and sees everything with unconditional love.
You can still be having your relationships and your favorite foods and whatever, but eventually we will let Holy Spirit choose everything for us and we will live in freedom. We may well remain with those we had special love with and no longer see them with specialness. But this doesn't mean we don't love them. It means we love them even MORE. We love them with an unconditional, ego-free love. One where being together is voluntary and not forced, or maintained out of guilt. But not until we are truly ready to accept this. It can't be forced while we still value specialness or we will experience sacrifice and loss.
You can still be in a one-to-one parternship all the way to waking up. Just look at Jesus and Mary as an example.