I think this is a very important point, even though what I say next is a bit of a tangent from the OP (and nothing to do with your response to the OP )
It's important because we are actually very very bad at predicting other people's actions through projection. Placing ourselves in other people shoes is akin to putting a cat's mind in a dog's body. We develop our own world based on our own experiences, adapting to the events of our lives to create coping mechanisms. Some people like certain body shapes because they remind us of our (secure, comfortable, etc.) parents, while others may reject it outright, or based in on their first love, or trauma, or... anything. The best examples of this are sexual fetishes - virtually everyone has some because the shift during puberty is rapid and "violent", meaning the onset is prone to having some wiring crossed. The point of this is that when we talk about "rules" for couples, you can't really create a model that fits people, only abstractions of them. Even the most abstracted generalizations, like "relationships should make the participants happy" begins to fall apart in the majority of the world's cultures.
The only answer to a "formula" of what works is descriptive. How do you have a successful relationship? Be happy. How? Be happy. Seriously. Just. Be. Happy. I can't tell anyone else (... well I can, because I like doing it (1)) how to fulfill their insecurities, needs, wants, desires and fantasies. I mean, really, how can you? I can't really understand being attracted to another male; I don't reject the concept, but this is a good example of me being unable to project myself into another person's shoes. My baggage simply doesn't transfer... but it's more obvious because of the difference in preferences in sexual attraction. I can't depend on projecting myself into anyone, and when I think someone else is "enough like me" to project and predict, all I'm doing is ignoring the bigger differences.
There is an alternative to this: observation. People's prediction of others' actions goes up dramatically when we observe and extrapolate and goes down when we ask ourselves "what would we do". And because I feel bad about not in some way making this about the topic in the thread, these are the reasons why I would reject the OP's position wholesale.
(1) I say all this, but there are ways of generalizing what one should do. Looking for equal value mates, or high/low trade offs on what you each want, etc. But this is still mostly description, no different than a "just be happy", except a little bit less off the cuff.