Everyone keeps hammering “Himari brought Ennamouto in first! Why is she getting mad?” 1. because she didn’t realize she was his first love, which brought in a bunch of emotions she was not equipped to handle. 2. She didn’t bring her in knowing that she would REPLACE HER, which is another heap of emotional stress she was not ready for. 3. Her long time best friend doesn’t pick up on the fact this is clearly bothering her, I mean it’s pretty fucking obvious with how she was arguing that she didn’t want it and MC didn’t stop for a second to think “hey maybe let’s table this for now so I can talk 1 on 1 with Himari”.
Their entire relationship was built on never falling in love with eachother, so it’s not like “oh just tell him you like him” is an option, so all she can do is try and make HIM fall for her first (thus the sudden spike in flirting). Then the more she flirts the harder he rebuffs her which drills the concern that even if she did try to confess or something that he would say no deeper and deeper into her head so that’s not even an option.
Hell she even tries desperately to calm herself down before the water incident, like shit was heartbreaking for anyone who’s had a panic attack before. She KNOWS she’s being unreasonable, she KNOWS it’s her fault ennamouto is there at all.
At this point she feels she has no options left at all and a time limit before she’s replaced so she’s desperate and every tool in her tool box keeps making things worse. She’s never even BEEN in love before and she has to navigate it under the worst possible conditions.