Isn’t that like the point of this manga or am I just into dark romance stuff?
No, this manga communicated since the beginning everything was consensual. They had safe words (or hand signs), ongoing checking in through dirty talk, talking to her normally. Poor aftercare, but still aftercare (cleaning her and giving her water and asking her if she liked it and if she wants more etc).
She told the blonde guy multiple times she doesn't want it and he manipulates her emotionally with "You don't want to disappoint Male lead?" Etc.
Look, there is nothing wrong with enjoying dark romance, but it's very important to know the difference between consent and no consent. Dubcon (dubious consent) technically doesn't exist either. If someone is very drunk for example it's not really consent. Paralyzed by shock is not consent.
For example the trend in porn and novels about choking lead to young people trying that in real life and even gender based violence towards woman.
Sorry for sounding like a worried teacher but it is a serious topic for me. Because fictional work is often influencing real life, especially thing people see in porn etc.
This guy is a red flag. Touching her without consent and then emotionally manipulating her.