Surprised so many people dislike Zoey and her writing tbh, even putting aside my biases towards her style and archetype, I thought she was really sympathetic in the interlude. She's not the first person to pursue their dream and realise it didn't live up to what they wanted, or the first to overlook the joys of their home, and she was only half of the poor communication problems with Tremolo after the move.
I do think it's interesting to try and suss out her role in the story, though. If it weren't for the interlude, I'd assume she was an obstacle to the relationships with the MGs and a demonstration of the dangers of clinging to the past rather than moving forward (feels like there's a lot of little moments in E9 about the potential dangers and downsides of having an ex around) ... but you don't create an entire solo episode for that character, from their perspective, trying to make them more sympathetic and put the player in their shoes.
Maybe whether having Zoey around is a good idea or not, and the lesson for Tremolo/the player to take away from it, is dependent on your choices, and that's why we could choose her alignment. Perhaps a DIK Zoey is more agressive and jealous towards the other LIs? That'd be hot.