This is fascinating. I realized that a model I have for evaluating relationships is basically another take on Albertus Magnus's model of friendship.<p>I'll start with Magnus:<p>Albertus, following Aristotle, distinguished between different types of friendship. He identified three main types:<p>Friendship of Utility: Based on mutual benefit, where individuals associate because they gain something from the relationship.<p>Friendship of Pleasure: Based on shared enjoyment or pleasure, where friends take delight in each other's company.<p>Friendship of Virtue: The highest form of friendship, where the bond is based on mutual respect and a shared commitment to moral goodness and virtue. This type of friendship is selfless and enduring.<p>Now, I'll run through my model, which I have applied to dating. I call the three dimensions: friendship, sex, and romance. You can have varying compatibility on all three dimensions, but in a sense it basically works out to Magnus's version above.<p>Friendship means shared interests. You like doing to same stuff and spending time together.<p>Sex is the pleasure compatibility vector in Magnus's formulation. i.e. how much fun do you have when you're together. Don't think of it just as sex, but also just like "wow this is fun and pleasurable"<p>Romance, people find this word tricky. I also don't think Magnus's idea of "virtue" hits it correctly either. It's basically a sense of tenderness and the deep-rooted feeling that you and the other person should have shared outcomes.