I would be perfectly ok with Bella beeing pissed but as the game lets you think this is not a problem during two episode and then suddently backstab you for this, it's really lame.
If Bella had told me this just after the scene with Cathy, it would be fine.
And you say it's not a harem game, are you kidding me, the whole game constantly push you and worse force to to that direction for what , beeing able to backstab you later and make choices for you so you are pissed

I have made a first gameplay before by trying to reject all girls and you can't really, so if you want a girl you need to reject all others from start or you will get fucked up well in the end.
And by playing this way you give up to all the fun content in this game, so what's the point, playing an anoying game just to maybe have the girl you want in the end.