I think that most of it was just lazy writing on SJM's part. She didn't give a slow descent into the relationship being toxic, we just flew through it so it felt like a weird fever dream for me.

I really don't like how in the books (I hope this isn't a spoiler) she treats sex as the end all and be all of a relationship that heals all wounds instead of proper communication and therapy. We get some actual emotional healing for Feyre, >! but it all just goes sex sex sex, and that magically healed most of the wounds. If something is bothering her, they talk for a second and then sex, boom problem solved (for a while) !< That is what really disturbs me the farther I am through the ACOTAR universe.