After being together for a long time, the excitement of the early days decreases. The relationship has not gotten worse. It has become familiar. But treating this change as proof of less love is what actually makes the relationship worse.
More and more things become predictable. Once they know what the other person will say and what they will do on the weekend, there is less left to discover, and they feel that as boredom.
Another reason is that less effort goes into the relationship. Early on, both try hard to adjust to each other, but once things are stable, they spend that effort on other things. The affection is the same, but it is expressed less.
Because they always get in touch first and make the plans, they start to feel that they alone are keeping the relationship going.
It is also hard to bring up. Saying they are bored sounds like blaming the other person, so they stay quiet, and while they stay quiet, they look for enjoyment elsewhere.
The need for novelty is not the same for everyone. Some people tire of repetition, and others need repetition to feel comfortable. For the first, stability means boredom. For the second, stability means contentment.
They also confirm the relationship in different ways. When someone who confirms it by trying new things together is with someone who confirms it by simply being there, only one of them feels there is a problem.
Instead of saying there is a problem in the relationship, say what you would like to try. Saying you are bored makes the other person defensive, but a suggestion to try something together is something both can act on.
The person who always makes the effort should say so. Waiting for the other person to notice on their own means they never will. A single request to take turns making plans changes how much each person takes on.
They start looking for reasons to break up. Once they conclude that boredom is a problem with the relationship, they keep gathering evidence that fits that conclusion, and even small things become proof.
The one making all the effort eventually stops. When that person gets tired and gives up, the relationship suddenly goes quiet, and only then does the other person notice.
What people call a rut is usually a difference in how much novelty each person wants. Knowing about that difference lets them adjust without doubting the relationship.
The relationship analysis describes why the two were attracted to each other at first and what changes once they become close. Knowing what decreased as things became familiar helps them decide together what new things to try.
This page describes behavior patterns for self-understanding. It is not a medical or psychological diagnosis, and it does not replace professional care. If difficulties persist and disrupt daily life, please seek professional help.
This page covers the type in general. How it actually shows up in your own combination is what the measurement tells you.