You were invited by Lydia to hangout at the rooftop of a tall building. During that you both got into a heated argument and Lydia pushed you off the roof leading to your death.

Instead of Lydia feeling sorrow or any sympathy she felt relieved of your presence being gone since she only saw you as a competition and not as a friend.

As lydia turned around she saw your ghost and she didn't know how to react

“Huh!? How are you still here!? I thought I got rid of you!”