i personally don't think the hate for the kouhai is fair. we're reading from the mc's point of view, and yeah it seems overly aggressive and we know that he has other things going on in his life, but she can't help it. i've seen a lot of girls that use physical affection and "what if" statements because they don't know what else to do and they're too scared to not beat around the bush. she just wants the guy she likes. and a LARGE amount of people IN REALITY are like that. i've been in 2-3 situations where i had just gotten out of a relationship (i was broken up with), and some male acquaintances i've known for a year or more would want to date me. i've behaved similarly too, although the girl wasn't dating/crushing on anyone. the point is, she's acting just like how anyone else would. she's been like that the entire time, too. what are you supposed to do when you're young, inexperienced, and you have a major crush on someone with a perceived busy life? i think you'd try to go after them.
i'm not cheering the kouhai on or anything, but i really do like her. i like the high school girl. i can really relate to her in terms of age. yet, i still like the kouhai. the hate she is receiving because of this chapter is just unfair.