@KazumaLee94 I think the idea is that at this point he wouldn't date her even if she asked him, he showed some interest in the first chapter but i'm not sure if he was really serious or if her antics turned him away.
I've read before that in Japan a lot of the idol otaku are kind of crazy and obsessed with idols being pure and untouched, so anyone dating her even himself would ruin the pure image he has of her as an idol.
She wanted to get him to like her as an individual rather than an idol by building a personal relationship with him, but he rejected her and doubled down on only liking her idol image, so that's why she's angry.
It's like being in love with a movie character instead of the actor.