Ayoung child asks his teacher, "how can love be real if you don't ever see it? " which branch of philosophy has that child's question tapped into?

The answer to this question is Metaphysics
Metaphysics refers to the fundamental question that asked a bout a core principal/belief upon something.
Learning Metaphysics will definitely help their child in understanding the complex situation of life and reality that he's going to face when he's grown.