If Chapter 5 is the finished game, (?) why not put it on Steam, give an email address to send proof of purchase to, then send out a free key?!
Yeah well Steam also updated their Terms of Service, it's now harder to have games with the subject matter being qualified for sale there. Sure there are games with this type of relationships on Steam, but those were before they updated their rules. I'm not a developer so I don't know all the details.
Censorship is constantly increasing these days. I have no doubt that they're going to tighten the belt even further, as are all other platforms. The safest route would be to stop making adult content altogether. I haven't decided to go that far yet, but the thought has certainly crossed my mind. We just have to push back as a community, and do everything we can to stop censorship from taking away our freedom to enjoy what we want to enjoy in fantasy stories.