Responses
the first few times she did it, she clearly wasn't looking to have sex with him because she didn't want to ruin their friendship. and yes, all mangas have that character (usually the heroine) who's super submissive, always says no to sex, super-pure... like damn sis, no one's gonna chop your head off because you like having sex

bruh their sex is so vanilla and it's like 2-3 positions max. dude you sleep together almost everyday, spice it up.
also a lot of the times it feels like Souma is forcing himself on her, all she says is no, stop, and doesn't give clear consent.
finally, she apologizes way too much. she's rarely in the wrong but keeps apologizing to him and putting herself down infront of him constantly. The only time she was ever remotely confident is when she was drunk...