Big losses are when someone we love dies. Finding out someone close to you has a serious illness. This is tough to handle, especially when you are growing up. And you think bad things can't happen to you. We all react differently to loss.
Shock is usually the first reaction.
We may deny that anything happened. Then, we get angry. We think life isn't fair. We may even get angry at the person who died, or got sick. Sometimes we feel a lot of regrets.