I'm completely fine with the optional sharing, but NATE should honestly be written out of the game, or at least give the option to kick him to the curb, I don't wanna be that weirdos friend. (Btw I haven't played the game, just going off what everyone else is saying + dev notes) Being able to get rid of him would automatically make me interested to actually try the game.
I've played a handful of games with sharing in them, I don't mind if it's a harem/romance game with optional sharing, or a sharing focused game, but anything with netorare (even if it's not technically cheating) that isn't completely avoidable/optional is just not my cup of tea. I know it's only at the beginning of the game (supposedly), but being forced to be the guys friend afterwards feels shitty, screw that.
Of course this is just my opinion and you should continue to make the game you wanna make, just figured I would share with you my two cents. You probably won't ever win the hardcore harem/vanilla crowd over, but people like me who are somewhat on the fence would probably be willing to give your game a go with that one single change.
Regardless, I wish you luck in your endeavors Dev.