He made it clear that there will be "unpleasant scenes" for some.
With this story of bad endings, I believe that DEV is supporting the idea that to be considered something like NTR, you need to have ties to the FMC, if you do her route correctly, she won't get involved with others.
Now if you decide to ignore her issues, she will get involved with other guys, and that cannot be considered NTR, you have ignored her route, you have no connection with her. For something to be NTR, you need to have a connection with FMC, I think that's what he wants to do.
If that's the case, I particularly like the idea