In my last post, I put forth the idea that the most ethical decision is often to prioritize our own happiness over that of anyone else's. This idea creates interesting implications for relationships, and polyamory in particular, especially given my position that polyamory isn't all about you.
Most relationships have built in the idea that partners' are inherently at odds with one another. As I've said many times before, rules only make sense if you anticipate that one or more partners will want to break the rule at some point in the future, and almost no relationships avoid having rules. Monogamy is one of the most common, but by no means most harmful, rules.
I try to have relationships where everyone wants the same thing. That way, everyone can do what they want as much of the time as possible. This doesn't happen by accident. Generally, people don't just randomly want the same things (though, it's probably best to start relationships with people whose desires are similar to your own). The way you make up the difference is by loving each other.
I define love as the mental state by which another person's happiness becomes linked to your own such that changes in their happiness cause corresponding changes in your happiness. I make no distinction between romantic love and any other type of love. A person can love a romantic partner, a family member, a dog, or all of humanity (though I wouldn't recommend it). When you love someone, their happiness makes you happy. It's in your self-interest to help them be happy in any way that you can.
Love comes in degrees, measured by how strong the changes in your own happiness correspond to the changes in your loved one's happiness. It's possible to love someone so much that your and their happiness become synonymous.
It's through love that we are able to focus on making ourselves happy while simultaneously doing everything we can to help our partners to be happy. It's through love that we are able to feel compersion, even though we're frightened. It's through love that we can do things for our partners that, to outside parties, look like sacrifices, but actually make us happier than we were before.