There aren’t any sex scenes in any of Tolkien’s material - not even insinuated ones - so this is definitely going to far into the “creative liberty” realm. I am shocked that the Tolkien estate agreed to this as they own the licensing rights to the material and have historically been good stewards of it.
Christopher Tolkien recently passed away. My guess is that something like this only became possible after he was no longer present to stop it.
"and it is called the Tale of Grief, for it is sorrowful, and in it are revealed most evil works of Morgoth Bauglir."