You can never know if a person forgives you when you wrong them. Therefore it is existentially important to you. It is a question you are intensely concerned with. Neither can you know whether a person loves you. It’s something you just have to believe or hope. But these things are more important to you than the fact that the sum of the angles in a triangle is 180 degrees. You don't think about the law of cause and effect or about modes of perception when you are in the middle of your first kiss.