Have you ever felt that your life is happening right out of a book? I feel that sometimes. Sometimes I remember what things have happened with a character and realize that just those things are happening with me. It is downright spooky!
If a single incident is similar to that in a book, you try finding out similar characters, similar situations, and perhaps similar feelings too. Or may be, you try to gauge what your feelings are at the moment the real thing is happening against what you thought about that incident when you were reading the book.
For example, you have read a book in which the protagonist had the misfortune of losing a family member. When a similar situation arises in your life, you are very much involved in the scene before you. But you are also watching the scene unfurl before you from a third person perspective. You would compare how you felt when you read that incident in the book. Perhaps, it is the difference of a third person perspective and a fourth person perspective. When reading a book, you are mildly aware that it is just that...a book. Things happening with the protagonist are just fictional. You are looking at things from a transparent fourth wall. You would probably 'know' that you should feel the sadness rather than actually feel it. But when you are looking at the actual incident in your life, you can feel the sadness. But you also take in all the other things happening around you at that time.
You notice your relative, peaceful in death. All other relatives respecting death and murmuring in low voices. Some discussing the plans for the funeral. Others remembering the once-living beloved. And the kids not sure how to behave with such a tragedy before them. Children looking at the dead relative and wondering how they should react. Should they cry, just watch, avoid the scene and sneak away to an unknown place, console their parents, yet not knowing if they would appear too grown-up if they consoled them, or just laugh out and stay unaffected. And you can see the elderly people looking at the dead thinking when their turn would be. You can see them thinking of that unknown time when they would be lying there, still and untroubled. The shadow of a controlled fear, a fear of the unknown.
And in the midst of all this you remember the poor protagonist in the book and think whether s/he felt the same thing in such a situation. You then ascribe your own thoughts to the protagonist and believe that life is rather frightening to present you with the same situations that were there in the book. An eerie feeling of déjà vu sets in.
But if you are in a happy situation, I doubt if you would remember about a similar situation in a book. What about a neutral situation, neither happy, nor sad, somewhere in between? Just an anxious situation, which makes you think about what you are doing at that moment. You might think how similar it is to a situation in a book. You then are all anticipation of what will happen next.
That's when you realise, life is too good to be true. After all, life takes inspiration from books!