In stave 2, "The First of Three Spirits," of Charles Dickens's classic novella A Christmas Carol, the Ghost of Christmas Past guides Ebenezer Scrooge through memories of the important people in his past, including his beloved sister, Fan; his first employer, the irrepressible Mr. Fezziwig; and Scrooge's fiancée, his first love, and seemingly his only love, whose name, Belle, isn't revealed until later in stave 2.
The Ghost of Christmas Past's intention behind prompting Scrooge to remember this meeting with Belle is perhaps to remind Scrooge of the last person for whom he felt true human emotions. In the scene from the past that the Ghost shows Scrooge, Scrooge has already turned his attention away from other people (such as Belle) and human emotions to the pursuit of money, which is the reason that Belle releases Scrooge from their engagement. Belle says,
I release you. With a full heart, for the love of him you once were.
It doesn't seem that Scrooge ill-treated Belle. She makes no mention of anything untoward between them other than how he no longer seems interested in her. "Another idol has displaced me," she says simply. He has no room in his heart for Belle.
Immediately following this remembered meeting with the young Belle, the Ghost of Christmas Past shows Scrooge an apparently real but not remembered scene. Scrooge couldn't have remembered the scene simply because he's not part of it—as he's been in of all the other scenes from his past—and he has no way of knowing it occurred other than the fact that the Ghost of Christmas Past showing it to him.
In the scene, which takes place only seven years in the past, Scrooge sees a young woman who he believes is Belle, "now a comely matron, sitting opposite her daughter." Her name still isn't spoken until the woman's husband enters the room to tell her what he's seen earlier in the day (the only time her name appears in the entirety of A Christmas Carol). The husband says,
Belle ... I saw an old friend of yours this afternoon.
He asks Belle to guess who he's seen, and for some reason Belle ventures a guess that it might have been Scrooge. Her husband replies,
Mr. Scrooge it was. I passed his office window; and as it was not shut up, and he had a candle inside, I could scarcely help seeing him. His partner lies upon the point of death, I hear; and there he sat alone. Quite alone in the world, I do believe.
The scene touches Scrooge deeply, as the Ghost of Christmas Past no doubt intended, and reminds Scrooge of "what might have been" had he chosen Belle instead of the pursuit of money. This is part of the lesson that Jacob Marley hoped Scrooge would learn by the visits of the "Three Spirits" which would give Scrooge "a chance and hope" of escaping Marley's fate.
It's interesting to note that although Scrooge makes a considerable effort at the end of the story to reconcile with his nephew, Fred, and make amends with Bob Cratchit and his family and even with the gentlemen who sought money for the poor in stave 1, Scrooge apparently makes no effort to reconnect with Belle or even to find out what's happened to her or her family.