Kana-yan still didn't know about Shima's feelings for Gen when they started going out and when they went for summer camping. He was genuinely happy about their dating and I think that it is normal to kiss your girlfriend/boyfriend even if it is a surprise. I mean for normal couples who are in love with each other, surprise kisses sometimes give you the gittery but loving feeling to each other.
Kana-yan just noticed shima's feeling when she reacted on the fact that he told Gen and Wao about their kiss and when Shima's mom preferred Gen over him. I'm not saying that what Kana-yan did to shima in his house is right but I think it is normal to feel frustrated when you feel that your girlfriend/boyfriend does not really love you while you are going out especially if you like that person.
Although Kana-yan wanted to treat Shima correctly and lovingly, he couldn't do that because of the doubts he had about Shima's feelings to him. I think he brought Shima home not only because he wanted to do it but to also confirm that Shima also loves him the way he does for her.
Kana-yan was just desperate and frustrated at the moment but I think that he will realize soon that what he is doing is not right and will let shima go.
Don't get me wrong but I'm also a big fan of SHIMA-GEN Love Team since the beginning so I am happy with the progress of the story.
He did say that his mom wasn't home. and honestly, she was a bit stupid for going in his room after only dating for how long? ridiculous.
Yeah but at the same time, you are supposed to be able to go into your boyfriend's room without having sex ? And she's a confused teenage girl looking for something to hold on to, even a not-so-great relationship. But I do get your point :)
Sooo... kana-yan knows or feels that she doesn't really like him, and kisses her out of the blue without any sign of consent(sexual harassment). He then talks about it with HER family and friends... And even when he senses that things aren't doing great, he brings her home without saying that his parent's aren't home, insists on doing it, and then when he asks her and she tells him that she doesn't like him... he tries to blackmail her into having sex so he will stop harassing her about it ? This isn't even weirdo psycho, this is a manipulative very intelligent narcissistic man.