As feedback for the Dev, if sharing is unavoidable, there is very little reason to make a non NTR route
I dont think anyone that doesnt like NTR will play an unavoidable sharing of your main LI
If you are sure you can make the sharing avoidable (which considering the premise of the plot, it isnt possible to make it avoidable), then i would suggest to only do the NTR route
The game is not for me, best of lucks for the Dev
I don't like NTR at all, but I'm not so strict about it that I can't enjoy any game where an LI has sex with someone else as part of the story. How about a game where you lure away an LI from someone else who doesn't deserve her, or where you rescue an vulnerable LI from an abusive relationship, or where you reconcile with a former lover who broke up with you years ago and married someone else, etc.? The possibilities are endless. Not to mention wife swapping, or orgies, or whatever.
Not everyone interprets "NTR" as broadly as some people on F95 do. To me, NTR is supposed to be about a pathetic cuckold who gets off on the humiliation of seeing their LI get railed by someone more manly and powerful. But the definition of NTR on THIS site has gotten much, much broader in a kind of weird way. Hell, some people on here call it NTR if every LI isn't a pure untouched virgin from the start. The only acceptable game is a pure harem game where the MC fucks everyone and the LIs are paper cutouts who have no agency of their own but to feed his ego. That's not how real life works.
All of that would be ok in the abstract. Everyone likes different things. But they get so angry about their broad version of NTR, and need to let everyone know how much they care about it and how heavily they self-insert intot the game, and then smugly call everyone who disagrees with them a cuck, and rant how the game is doomed to failure unless the developer remakes the game to their satisfaction. They write bad reviews of the game because it isn't the exact content that they want, or the developer didn't program the game so that everything they don't like can be opted-out from, even if it ruins the story that the developer is trying to tell.
It's just so tiring and annoying and it happens over and over and over. Let the developers make whatever game they want to make. If you play one that isn't to your liking, play something else. It's just pixels FFS. It's not really you. You are not getting cucked by pixels. It's a game. Relax.