Dunno if it's bad writing but...
Okay, so Heronia just met Cecil in the academy when she enrolled, didn't knew about Bertia meddling with the story and made change in Cecil for good.
She was supposed to meet the damaged Cecil when they first met, but he avoided her chase after Pii.
Then he ignored her when she was sleeping under the tree, he avoided to explain why, just went on the walk with Bertia.
Cecil bailed from Heronia when she got locked in the empty room, without explaining.
When unexpectedly Bertia got bullied by the whatshername, Heronia took it as revenge of jealous girl who partner got interested in Berita (this was true, he got close to Bertia) so she thought Bertia was rightfully evil.
Courtgain didn't tell Heronia about Bertia father acting as a spy and not being evil, reason why she accused him of being bad.
Heronia was kept in the dark the whole time, being ostracized from all information and thought the real world is just like the game and just now compared to Bertia who had plenty of events leading to realization that something is off.
Heronia didn't had "plenty of chances to restart", it's not the result of "her actions" but Cecil with everyone around avoiding her and telling things aren't like in the game...