Friend in one-sided love?

My best frend is in a problem it's one-sided love..omg i know her since 6 years but for the last 2 and a half year she met this guy & cudn't get him off his mind no it was not a love at first site ( she met him in aug and fell for him around december) But he dsn't love her back. She's alwayz sad & depressed we all try 2 explain her but she sayz she cannot forget him & move on she rly loves im from deep down i jus want my old frend bak. The worst thing is she even tried commiting suicide by eating lots of pills., we went 2 c her at the hospital but she's fine now. She told me once that she called him but he was swearing bakk at her wen she told him dat i luv u.Mostly she's jus quiet & nvr says anything if we ask she says o i m tired & makes excuses but She's not forcing him 2 love her bak ( she jus want him 2 stay happy, also she says that he dsnt deserve a b***** like me...& that makes mee sooo sad) i dunno wat 2 do & she's only 16 & d guy is 11..she said that she cannot live without him & wud only live with him. Does age rly matters in love? I dont wanna loss my best frend!! PLZZZZ Help!!