My god so many immature teens in the comments. People this story is set in Japan for the Japanese audience keeping Japanese society in mind. They could not just"date because you are not blood related" as societal views and reputation are quite important in places like Japan. If you have a bad rumour about you,you are shunned by everyone. I am quite worried about you people if you think dating your step sister is ok even in western society. Y'all have definitely been reading and watching too much step sibling stuff that you have lost a grasp on what is actually normal and abnormal. Also this "trope" of cutting hair is not a trope but quite a common thing. Whenever someone goes through a breakup or wants to overcome their feelings they change their appearance-dressing more flashily, dyeing your hair, cutting your hair is quite common. While cutting hair is often seen in manga, it's because it is the most obvious change that can be visible in manga format as well as artworks.