There's a few reasons, actually. If they're dead... 1) I don't have to care about them anymore because they'll be happy. 2) I don't have to worry about them because they'll be safe. 3) They can't hurt me anymore. 4) I won't hurt them anymore. 5) I have seized any bad things that may have happened to them. I doubt I actually would, but I'm not overly fond of these thoughts. Is this the symptom of a curable mental disorder?