Why do girls cry over celebrities ?

My sister cries over her favorite band a lot she's upset she has a crush on one of the bass player but he's married. He's too old for her he's even too old for his wifw he's 60 something she's right around her age. She cried because she saw a picture of them together she'll never be able to see him he lives in another country it's too far for us to go he rarely comes here because of her health she can't fly on a plane. The other day she was upset because it was his wedding anniversary she cried about him all day. Why do girls cry over celebrities ? How can I make her feel better ?