What is the key to strong relationships

I really like to observe the world around me, people, and the development of something. And here's what I've noticed.

In the past, almost all marriages/couples remained merged with each other for years. That's how long-term marriages existed. Merger, the framework of society, morality, principles, and duty. But back then there was no such attention to psychology as a science and to the individual in general. Nowadays, most people are engaged in self-development and develop their personality.

Psychologists help people to work on individualization, to develop their personality, to know themselves, their boundaries.⠀ But I am confused by the fact that there is a certain distortion. Since we have experience in building relationships in merging, but we do not yet have experience in building relationships feeling our boundaries.

Because we are like "children who finally got a long-awaited toy" (our boundaries). We began to feel them, and they are ours, we are greedy, of course, and we are very protective of them from everyone, especially our partners. And it turns out that in such couples there are not two loving, listening people, but two "kites" protecting their boundaries. If it's not, what is? The merger stage is a natural stage in the development of relationships, for bringing partners closer together. But it is temporary and should move on to the stage of "life's journey in parallel along the course set by both of us". With its own boundaries, but flexible and elastic. Where everyone does not break through or defend the boundaries to the last blood, but is ready to hear, talk, look for a new way, a way out. Sometimes to give in, and sometimes to insist on their own. Everyone should have time for themselves, but not too much, but in a way that is tasty!

Only a man's intelligence, authority (which belongs to him by birthright), and a woman's wisdom, cunning, and their common desire to be together are the key to a strong relationship.