I think a classic 3-way ender would be the best option; good end, neutral end, and bad end. Or at least something similar to that. Don't get me wrong, I love extremely dark NTR that ends in tragedy, but far too many lean into the shock value of such a thing and go all-in on the edginess just for the sake of it, usually resulting in a poorly written mess of a finale that jumps the shark and leaves a bad taste in your mouth. For example, there's a manga wherein a centaur girl is stolen from her human boyfriend by a male centaur - great concept, good execution. However, in the last page, the boyfriend takes his own life. Hot in concept? Of course, make it dark. Hot in execution? No, because it's so completely out of nowhere and weirdly mean spirited that it's a total boner killer going from this basic NTR story to a panel of some guy offing himself, lmao.
I understand that the previous game this developer made - which I've never played - involved the main character dying after being run over by the girlfriend-nabber, which could likewise be considered jumping the shark for the sake of shock value akin to my example. I've got no doubt that at least one ending is going to be Anon getting eviscerated in some way as Sana has kids with the main villain or whatever, and I would in fact enjoy that, but I'm hoping that the corruption system is an indication that our choices will at least matter somewhat and it won't be forcefully grimdark. Maybe the good ending would be a sort of secret end which you unlock through a challenge, making you work for a lovey-dovey marriage epilogue or something. However, it's also likely that it'd involve a final tease where Anon and Sana marry and have a kid, but she still cheats on the side, despite being happily married. Either way, I'm just looking forward to more content for this game, be it what I wish for or not. I just think that a generic yet sweet finale as an option would be sweet.