Just remembered there are younger members on the forum: as a warning, this story is definitely for 16+. There is harsh language, dangerous situations, and sexuality throughout.
Is it really that necessary to have an age rating on your book? If someone finds it too intensive, they can just stop reading. It's not like anyone will be traumatized by words that they already know.
FWIW I have been playing RuneQuest since I was 10 and the scenarios have always contained harsh language, dangerous (player characters having to resort to cannibalism tier) situations and sexuality, and half the time I have been the one coming up with them. I don't think that has really affected me in any way except for getting me hooked up on RQ.
Age ratings can be helpful. Some people would rather not read certain things, even if they wouldn't be traumatized by it. And some people actually
might be traumatized by certain things, which is why "trigger warnings" are a thing on the internet. We give ratings to video games, why not books?
Also, Donald is absolutely right that staring directly at an Eclipse is dangerous. You should avoid it whenever possible. You should also avoid staring directly at Twilight, New Moon and Breaking Dawn. Repeated exposure to any of these four may cause brain damage.