Say goodbye.

I don't understand why say goodbye is so hard. My life have been full of goodbyes and tears. I don't live with my complete family. My mom lives in another state with my 2 sisters, my father lives in another district with his wife and my little brother. I have another brother, son of my father who lives with his mother on a farm. Me? I live with my grandmother since I was born. No parents, no brothers and sisters. I only see them in my vacations...so, my life is a constant goodbye. Poor heart, he is used to see people who I love going away. It's normal. Still, I don't understand why say goodbye is so hard.