Why cant people live that way? When there is mutual attraction, they can just live in the moment and try to experience positive feelings as deeply as possible and when it starts waning, let go with warm feelings gracefully. This memory imprints of this in both would be powerful and what can be a greater reward than being part of another one's dream. After all we all live in the mental consciousness where memory plays an extremely pivotal role.
Its like, you see qualities in that person you deeply admire and focus on these dream qualities. The other person does the same, tries to find their dream in you. And when you get a match, try to go to the deepest experiences till its comfortable for both. This also means both should have advanced communication skills, high emotional intelligence with diplomacy, similar level of self development and overall intelligence as prerequisites.
Enjoy and savor these experiences, etch them in your memory and radically increase your sense of well-being. Its a pure win-win relationship or rather a 1+1=3 kind of equation.