Can be unlocked even if the game is a buggy mess (I unlocked this achievement on the day one patch, and you know that was not easy lol)
Anyway this can be hard to unlock if you don’t know what you are doing or get cornered a lot by the killers.
Always save when you find a mirror with the metronome. “This will not allow you to unlock the Blissful Unawareness achievement if you don’t be have it unlocked” (Note, if you save and you somehow will end up dying, immediately quit the game and load back up the save before you died (not the autosave) this will not count as you died. However if you load up the autosave it will count as you died therefore you will not unlock the achievement)
If you get hit, which you will, always make sure (when it is safe) to find the save location, (AKA the mirror with the metronome) to heal by pressing and holding the X button.
Always make sure you have at least a defense item (especially when you go into a new area or load up a save) and a diversion item to throw at the stalkers if they get to close to you (however sometimes when you throw diversion items at the stalker they won’t be stunned due to a bug in the system)
If you need further help watch “how to defeat (said stalker)” videos on YouTube or even walkthroughs on the game.