To dream that something or someone is fake suggests that you are pretending to be someone you are not. You are putting up front because you are afraid to show your true self.
To dream that you are faking your own death suggests that you are looking for a new start. You need some change in your life. If you dream that your significant other is faking their own death, then the dream represents something new that you are learning about them. Or it may mean that they are not who you thought they were.