The only mix up here is that you and I have different definitions for what "good ending" means.
If you get your sister pregnant in fantasy and don't have high enough stats/money, you will get a bad ending where she hates you, explodes, etc. (I never got the bad ending, so I don't know the specifics)
But if you do have sufficient stats/money, you get a good ending where you retire from adventuring and live happily ever after with your pregnant sister/wife.
In both "endings", the game ends. Apparently by your definition that simple fact makes either ending a "bad ending", but clearly I (and several others) disagree.