Alright I get what you’re saying now.
If it’s possible for the protagonist to die during a game (not taking into account RPGs), he usually dies if I play without a kouryaku. If it’s possible for an heroine to die in an ending, she usually dies if I play without a kouryaku. Obviously, it happens pretty much every single time I try a demo in which such an event is possible.
It’s one of the reasons why I usually use a kouryaku. It seems I’m only able to get “bad” endings. ^^;;;;;
Something must be wrong with your morals. 
That happens to me at times especially when the developers decide to use branches that have nothing to do with morals/ethics/etc. For example, perhaps you are asked to pick a location to go to at a branch point like (Mountains, River, School, etc.), and then you choose the wrong choice and the developers make the choice here crucial to the type of ending you get. Personally, I feel such cases are incredibly dumb. Like if choose mountain and that gives me a bad end. wtf? It makes no sense. I can understand some cases like maybe you are rushing to find someone and you have to know the history of a character like maybe where they always go when they are sad, or maybe a location where you first met them. Sure it makes sense then.
A proper branch point should be something like: Help her out, Ignore and side with the others, etc. Here it comes down to the players morals. What is the right thing to do. These are perfect branch points for determining if you head towards a good or bad ending.
Actually I like to cheat a little bit, and pick one choice and see the immediate results; and then load and try the other choice and see the immediate results… lol especially useful when the protag corrupts my choice!
It probably also has to do with what kind of games you play. If you mainly play games where you just have to keep picking one heroine then I would believe the results looking at it now that most people do get good endings. If people played other things than that where good endings depend on multiple conditions that aren’t all that related then they’d likely get bad endings most of the time by probability unless they cheat with the saves or use a guide. I like the later and I get bad endings as I said.
x-change 2 and 3 were a bitch without the walk-throughs