“Tell me one thing. All those facts and figures I saw of the Doctor’s life, you were never alone. Al
“Tell me one thing. All those facts and figures I saw of the Doctor’s life, you were never alone. All those bright and shining companions. But not anymore?”“No.”“Might I ask why not?”“They leave. Because they should. Or they find someone else. And some of them— some of them forget me. I suppose in the end… they break my heart.” -- source link