I think Kei is a very badly structured character that a human being can fall in love with someone just by knowing him for a few hours (chapter 4 for example) and the one who says that this is not a romcom has not read what he says in the Description of the volumes on the author's page is focused on that theme and of course the heroine is Himari, not that he is a yuri, in the case of Kei, to be a childhood friend, he does not approach anything and specifies that he knows the brother Since they were little, an abuser who uses an old friendship as a means of oppression has been more similar to boku no hero kacchan, but the only difference that Kei developed a desire for possession in front of Himari and sees him more as an extra subject, which I detest, you believe that the author does not know that he made a mistake in structuring Kei, with a single poorly designed character he can damage a manga and I assure you that in the next chapters there will only be two options for the author
1. fix Kei and modify the personality, she could be a tsundere (not a misandric) she could have feelings for Himari but as a younger sister not as a lover, and to solve the relationship with her brother she may develop feelings of brotherly love, and the brother should also improve his personality as being more attentive and also have the character to talk to Kei so that he stops being a possessive impulsive
2. This option is to leave things as they are and create an atmosphere where the focus is only on girls' love relationships, but from the start it would not work since it would isolate many characters such as the president and brother, making it become a generic yuri to the At first it attracts attention but in the end it will not last many chapters since that method of forced yuri manga does not work, even the most successful yuri does not exceed 40 chapters and all the work of the other characters will be only air.
I think that the focus should be changed but it only takes two volumes, maybe it will change Kei's feelings, since his thing is seen as jealousy of Himari's brother for not having someone close to him, but rather Kei is more like the affection of an older sister and that is what What Himari sees in her, in case of the good brother, maybe she has feelings for him, she is a childhood friend, and I think he is her only friend (since she has a disgust of personality) and stop seeing him as some kind of stranger.