Remember Zoey hadn't intended to end her relationship with the mc for good. She wanted him to go with her. And then when he chose to finish high school, she was still hoping he'd join her later.
Things got muddied when Zoey got lousy advice from her new friends and when the mc got the impression she'd found a new boyfriend.
But initially, and finally, Zoey actually wanted to be with Fuckface.
So that's why she returned in the end, when she realised her dream was nonsense and she was already happy before.
To ask, "Why now?", well shit happens when it happens. Often it happens when it's not very convenient (of course it would have been more convenient if she'd been around all along for the mc to line her up all the girls he liked and make his choice, but this isn't "The Bachelor"...).
When the mc made his choice, it only included the girls he had in front of him. It wasn't a surprise that he finally decided to stop stringing the girls along, he'd been feeling guilty about doing it for a while, so because he
did like them, he decided to let them go. He may be a DIK, but overall he's a good guy.
But now Zoey arrives when the mc has moved on, except the only reason he moved on was because he thought
she moved on. If that misunderstanding hadn't happened, the mc may have ended up travelling to San Diego and this would have been a completely different story.
But that didn't happen, and now it's going to get complicated.
And one of the main reasons for the complication is that Zoey has come back because she wants to be with the mc.
That's a big difference when compared with the rest of the LIs.
- Jill kinda fell into a relationship with the mc. She's nice to him and all that, but until the end of episode 8, it's not like she's heavily pursuing him,
- Bella spent half her time with the mc trying to fend him off and then giving into her own need for sexual attention. If the mc dumps her, she's sad but she'll get over it,
- Josy really likes the mc but she's pretty much just going with the flow (although of all the main LIs, she seems to be in love with him the most),
- Maya is mostly wrapped up in her own feelings, amazed that she's actually not a lesbian and also just seeing where things will take them; and
- Sage has actually been very forward towards the mc, but she's hardly phased at all when he denies her advances or ends things with her.
But Zoey is coming back for the mc, he's what she wants in her future. She's not going to give up without a fight.
Of course the mc could just tell her to fuck off, and I'm sure some players would like just that, but I doubt very much that's what's in store for the game. I'd be surprised if she's just going to be a cameo in the next episode.
The fact that she finished high school via correspondence means she's set up to somehow become art of B&R.
So my guess is she's here to stay. She is going to rock the boat a bit, but in the end I wouldn't be worried about not being able stay with the LI of your choosing, it's just more drama. That's pretty much what this game is all about anyway.