Isn’t she? She’s in love with Kou, but she chose to be with Touma. Although Touma took advantage of the situation, Futaba should have dealt with her heartbreak on her own instead of dragging other people into it just to prove to Kou that she can find someone else. As Touma’s friend, he just doesn’t want to see Touma get hurt.
i don’t believe in calling women “bitches.” its misogynistic, so you should stop that too. and when he calls her a bitch, she was actively trying to move on from kou, he’s the one who dragged her to the staircase to announce he was going to win her back no matter what. they’re in highschool and navigating first loves, she was trying to deal with her heartbreak in her own way but she has two boys who want her equally who got with her at awkward times. at this point in the story, touma clearly knows he doesn’t have futaba’s heart, but also knows she won’t be able to break up with him unless he agrees, which he has to in the end because futuba is the type of person to make sure they talk it out. and you can support your friend without calling a woman a bitch.

i need that guy who called futaba a “bitch” to die. just die. was this ever addressed? he just calls her a bitch and moves on with his life ugh