@starburst98 it's been a bit since I've read it but I do remember You trying to blackmail him into being her boyfriend. Then in The First Regret she mentions that if only she fell in love a long time ago then says "if I had noticed." Which I think means if she only noticed she was in love. It also mentions "since long ago" with older uniforms implying before he got together with Yukana.
It's also mentioned her fans know she is in love with him because Boa is always hung up on doggy. She is hung up on doggy even before the train. You could say it's jealousy over not worshiping the ground she walks on. But again, her followers think it's love. Also, she gets flustered before he picks her up https://mangadex.org/chapter/102236/12 .