It's the Japanese mindset. Basically, a woman should always be embarrassed, meek and coy about having sex and during sex. Even when they portray them as having some sexual agency, like Chiaki does, she still needs to keep that innocent, meek trait so she won't appear to have "loose morals" or something like that. Otherwise she falls into the "fallen woman" trope, even though that's not remotely accurate.
I want to thumbs up this comment.
This trope Japan has where the woman has to beg and cry during sex or pretend to not understand sex...even though they're a grown adult, happens in every smut manga. There have been times where I was just put off or completely annoyed by the screaming and tears.
I’m sorry, but I’m getting tired of these manga creators treating normal sex like it’s rape. No matter how many times Chiaki and Daigo have sex, she’s always screaming at him to stop, as if she doesn’t enjoy it. She doesn’t appear to even want to stimulate him either. And always acting like they’ve never had sex before. It’s so nerve-racking.
As a female reader, it’s a massive turn off how she’s behaving. How am I supposed to enjoy this if she’s not enjoying it?