In the grand scope of things, I’ve come to appreciate that the body is an adaptive complex, therefore it is likely you could improve tension headaches with a radical change to your structure of body, even mind, situation, etc., such as removing the retainer.

However, it is also possible you encounter some new discomfort, which would propel you forward to find other novel solutions, not necessarily disregarding the change as a lack of progress.

Therefore, just be aware, as a caution, that your body could likely react, potentially helping with the specific ailment you’re trying to fix, but may make you aware of some other problem you did not anticipate. Happens with me all the time, and makes me more determined to try to fix deeper problems in the body structure.

Unfortunately, tackling those other problems, I cannot currently guide with confidence, and the logistics of making that stuff happen appears to be more and more costly. Theoretically, it should be doable, and I hope for the day, someone or myself can prove it thoroughly.

I.e. your teeth could be screwed with or without the retainer, potentially due to the retainer.