She's acting like that because she's mad. She's torn between wanting to support Nakano and still feeling hurt from being rejected.
I'm not really sure this has anything to do with Toda, I think she's just feeling frustrated that her friend complains about using her powers but doesn't actually put in the effort to get to know or be close to people without it.
Now seriously, Mana's being a bitch for no reason and I'm starting to really hate her in this manga. I thought she turned good? But no! Not for us fellas