so what, the game ends in tragedy as the main character's ruined all the girls lives, and the only thing you can do is make the ending marginally less bad? Well so much for choices then! All this foreshadowing about "will you save them, or lead this island to ruin?" and it all comes to mean jack shit because we can't do anything positive for them. Traitor!
Depends on the character, really.
Yoko & Rina: You can actually help them by giving them something they always wanted. Rina's life was pretty terrible in her organization and she has self-image issues. Both of which a hentai protagonist is ready and willing to help with. And for Yoko you can fuck her brains out *and* show some basic human decency. In fact, while the game will not call you out on not showing her said decency, it *will* call you out on not fucking her. Priorities.
Mio: Gets everything she wants anyway.
Juni: Dies.
Gloria/Kaoru/Jessica: Get good endings if you don't dick them. Gloria does get a slightly better one if you do dick her, at the expense of Mio's sanity (edit: for clarification, Gloria gets a slightly better ending than Kaoru/Jessica if dicked, I am not claiming her dicked ending is better than her undicked ending).
Laoise: It's a blue and orange morality kind of neutral. If you don't dick her she the island's idol... But does it matter? Not to her, really. It's kinda hard to ruin her life.
So yeah, for most you can do something positive, for some you can do something positive AND dick them, and for some you can't do anything positive.
I do wish there was a positive dicking option for Gloria/Kaoru/Jessica, but them being who they are, I don't exactly see how you would do it. Besides Gloria. Gloria could just come out with the secret and be pleasantly surprised. But Kaoru and Jessica? One wants a normal relationship but you NEED to dick Mio, and one is grieving in a self-sabotaging kind of way. But still, due to the nature of the island, I wish we could help them come to terms with who they are. With our dicks, of course.
You can. By not picking obviously morally horrible choices (that game even clearly tells you are bad). Do you really expect to pick options like "That's horrifically unethical. Let's do it!" and get a good end with the girl?
To be fair, this is not the choice that fucks Jessica up, she was condemned to the bad ending the moment you dicked her. The impregnation is just the cherry on top.
The game calling the player out on not dicking the maids and then calling us out for dicking Jessica/Kaoru and fucking up their lives does feel a bit schizophrenic, looking back on it.