It's not just grief. There are as many emotions as there are people. The fragility of someone who lets their anger get the best of them... The strength to overcome fear because of love... You can't comprehend anything about them.
People aren't as complex as you think they are. They're simple, and they get sad or angry over simple things. That's how they are. They're quickly affected by the littlest things, and live without knowing where they're going to fall down. That's who people are!