I am a bit concerned about how long the game can be sustained with two main woman on the island. We know there's one more from personal experience, and might be another. But the game has already been focused on the mother and cousin. I've also heard people here refer to the cousin as the sister, although I can never get the incest patches to work. Or they just don't make enough references later in the game for it to make a difference. But it's another game that gave us too few love interests and is now trying to put in more content that game wasn't really designed for.
The dev needed to plan ahead a bit more. Have the MC marooned with a future harem of aunt, cousin, and some of her female classmates. The sister and mother are found later, or even better, rescued. Instead we've got too few love interests with too slow progress for how much time has passed. Once we have vaginal sex with the mom, that kind of signals the beginning of the end. So now is when they're putting in the flashbacks and seeing what other characters they can work in, even if there's less of a connection between the MC and the newer characters. Or we get the flashback that doesn't even involve them directly.
We could be working our way halfway through the original harem right now, banging a range of different young women, the cousin and also working on the aunt, while we try to find where the mom and one- no, two- sisters may be for the next season. Instead we had a story arc and number of love interests that should honestly last us through a single season, however you want to define that.