I'm also extremely confused why it's a big deal...it felt like a natural thing for this character to do and it's SO early in their story for it to even be a big deal. I highly doubt it'll even come back again in the story because it doesn't seem important to their relationship and is more about Saeki's character.
For real, all these comments about him being an asshole going with the girl and even ASSUMING they slept together LIKE HELLO? they didnt even show it so it didnt happen, they just went somewhere to party for pete's sake, and he's a social person so he found it hard to say no
I’m a little confused on why people are upset that he potentially or should I say ALLEGEDLY slept with the girl… From the beginning you can even tell he has a “people pleasing” attitude towards women he just can’t do anything but try to satisfy them to make himself feel better without letting them down. Plus, they’re not even together yet even tho it morally wrong at least he’s realizing his feelings instead of playing hop scotch with Oka and dating him while sleeping with others.