I agree with you 100%. Too much thought and exposure to long hair or, for that matter, any fetish or fantasy ruins it. I remember the times when I was not addicted to this, and I was not actively searching for long hair content. At that time, seeing a rapunzel somewhere on the streets or the TV unexpectedly gave me goosebumps and excited me.
Now, unfortunately, just one click and I can see it all. After a point, it gets really stressful and you start to lose interest because your brain is now too used to it. And the worst part is if it becomes an addiction, even though you might not be actually excited, you force yourself to like it and enjoy it. That is the worst. I feel your excitement for hair should be natural. And it can be natural only if you do not consume hair-related content regularly.
It is like food. You can have your favourite food daily at max for a week. But after that, even though you used to love it, it is now nothing new and loses it's value for you.
My suggestion would be to just take some time off and completely avoid any hair-related content for a week.
I was facing the same problem and I completely disabled Instagram, YT, and other places where I could be exposed to this for 3 weeks. And believe me, 3 weeks later your love and interest for long hair and rapunzels would be like it was for the first time you realized your love for long hair.
I really believe images and videos have ruined us and our expression of love and lust. Like someone said in one of the earlier posts, watching pictures and videos is not real stuff. It really shows that we are not capable enough to get the real girl that we want and, hence, are resorting to such stuff. That is the worst thing one can do because only your eyesight, maybe touch, and hearing are active. But real love involves all the 5 senses or probably the 6th one as well.
So my advice would be to just completely isolate yourself from anything that can force you to watch something for a few days.
Cheers! I am open to any arguments or different thoughts.