Practical advice is: let nature take its course. After two people have been together for a long time, what are their habits, and they will always be like that in the future, and they will reluctantly accommodate each other. Later, their feelings will become weaker and harder to accommodate, which will only lead to constant quarrels.
You should reflect on yourself first. Is it because you two have cooled down, or do you personally feel that you just like the new and hate the old, and you are tired? If it is because of two people, then consider what you are happy about, what problems you can solve, and what irreconcilable contradictions you have; If it is your personal emotional burnout, then you should consider that it may be your temporary "affectation". If you change your partner, it will still cool down in a few days, and if you don't change your partner, it will also cool down. This is your own nature, and your life is spent at a low temperature.
Don't ask what to do, leave, solve and reconcile. I don't think about what to do, but I dare not say it. Don't be reserved, cherish your feathers. If you can't hide them, say it early and solve it early.