Long drawn out theory - A lot of the 'bad boy romances' that are super popular nowadays are because the authors and readers have vaguely shitty/inattentive boyfriends and it's a way for them to reframe it as Super Romantic.
In ACOTAR Rhysand tells her what to and controls what she wears in one scene- because he's protecting her. When he's cold and callous it's because he can't let his true feelings show; when other love interest Tamlin does it he's the wrongun but Rhysand doing it is because of TRUE LOVE and their are Fated Mates. Its very similiar to that one white trash couple you know where he beats her and she keeps babytrapping him posting about being 'twin flames' on Facebook; cope because they can't/don't want to break up. They are MEANT to be together.
There are many other bookboyfriends like this - Xaden (Xayden?) in fourth wing is bit sexually pushy but it's okay because he just wants to bring out the 'darkness' in Violet (or Violence as he calls her) and he can't control himself around her. If the love interest is part of some evil organisation/enemies to lovers trope, she fixes him and all his previous shitty behaviours are redeemed by their love and he's a Good Man (even if his actions in the narrative are still questionable). Again if he's the distant, unemotional type, its really because she makes him feel all these confusing, overwhelming emotions, and his love for her scares him but together they can make it work and when he's brooding and moody and bad tempered, he still loves her.
When you look at the authors (Fourth Wing for example) they often have military boyfriends or husbands or are surprisingly Mormon/Fundie adjacent. No shade to the military but your average Joe or average Utah man is not boyfriend of the century imho (I've posted about Willow Winters the 'spicy' writer before and her and her co-authors boyfriends all seem the fairly inattentive husband type, there's actually a few discussions about how writing the novels they do 'brought back their relationship').
Writing (and reading) these books where your shitty, uncaring boyfriend who is rude, jealous, controlling, or just a not great guy to be in a relationship with all, imho turns it into 'he really does care' and then you don't have to worry about him or your relationship anymore. There's a lot of small scenes in these books of the MMC taking care of the FMC (literally 'i bought you soup for your period cramps' scenes) or very very in Touch with his emotions after a big revelation that all his terrible behaviour to her was not him not-caring but him caring tooooo much (think Mr Darcy but in every single book without a shred of the self-reflection of Darcy and Elizabeth imho). There are definitely other things going on like the obedience stuff and a lot of romance is obviously just female fantasising about 'Man taking care of you/Man ordering you around' but the overwhelming presence of it in booktok/modern contemporary imho is not a great indicator.
There's a genuine argument you see sometimes in bookish circles that these new book boyfriends are incredibly unhealthy because authors and readers present them as PERFECT BOYFRIENDS true love (there's also something to be said about how the other love interests (Tamlin) will be immediately presented as mega abusive as well, very bpdemon imho), and the age of girls getting into bookish circles is getting lower and lower, while smut scenes in YA are near unchecked and the behaviour of some of these men is pretty awful. Controlling, rude, demanding, doesn't care for her opinions, questionable age gaps, locking her up, 'I know what's good for you', etc. It's not a great example to spread unchecked in modern lit and in almost every fuckin book.
Sorry if long and rambling, it's a theory ive had for a while looking at how popular it is and some of the authors relationships (I love to snoop) and some authors/readers posts. I think it just makes them feel better about their dating choices or lack of choices and being unable to speak up for themselves or something.