What to learn about anything or anybody? Find the engine.
An engine is something that moves, making something else move towards or away from itself.
The electron is an engine that uses photons as it intake and exhaust.
A human finds happiness with friendship as its intake and exhaust. Give and take. Back forth. Communication. Heave-ho. Friendship makes an engine that makes you bigger than yourself, because now you include _another_ in your happiness. And you are included in their happiness.
And there’s the cycle and all you need to know about human relationships.