It really depends. How many death endings are there? Is the game challenging to make the correct decisions? When and if there is item usage, is it obvious to use the item? Or do you need to search around for the answer?
Depending on how you're game goes, it will be difficult or easy. Usually, I'd suggest that a difficulty of 4 or so for games that don't have true endings, and that it's hard to die in. Of course, if it's easy to die, and that most choices end in death, then it should be difficult, and rated higher.