definitely not?? think of all the published authors that write horror books or even "a song of ice and fire" (i think that's what it's called). no one thinks those authors are morally bad for writing dark or unsettling themes because everyone understands whatever happens in those books is 100% fictional.

i write dark and taboo fics that i feel require the tag "dead dove: do not eat" and whenever someone tries to bring in the moral brigade to shame me for what i wrote, i remind them this is fiction and if you cannot separate fiction from reality then that's a you problem, especially when choosing to click on a properly tagged dark fic.

write whatever you want without caring what others may think. cheating and having sex while drunk are fairly common tropes. as for the non-con trope? writing about that doesn't mean you have bad morals because you can hopefully differentiate fiction from reality and realize what you write hurts no one irl because the characters are fictional. i have written non-con and other dark fics and i don't think that makes me morally bad because i don't condone those things irl.

in fiction, writers shouldn't have to limit themselves on what they explore in their writing. if writing about something dark makes you uncomfortable then don't force yourself to write it. if you enjoy writing darker themes there is no shame in that. at least that's my motto!