That’s what life is about: People come and go.
Not everything is supposed to become something beautiful and long-lasting. Sometimes people come into your life to show you what is right and what is wrong, to show you who you can be, to teach you to love yourself, to make you feel better for a little while, or to just be someone to walk with at night and spill your life to. Not everyone is going to stay forever, and we still have to keep on going and thank them for what they've given us.
For all things come from earth, and all things end by becoming earth.