Andrée, perhaps not an altogether reliable person, has given Marcel the reason why Albertine left him.
“…I think she was forced to leave you by her aunt who had designs for her future upon that guttersnipe, you know, the young man you used to call ‘I’m a wash-out,’ the young man who ws in love with Albertine and had asked for her hand. Seeing that you weren’t marrying her, they were afraid that the shocking length of her stay in your house might prevent the young man from doing so. And so Mme Bontemps, on whom the young man was constantly bringing pressure to bear, summoned Albertine home.” (V,830)
Marcel, who had been so engrossed with his jealous speculations, had never once thought how his living arrangement with Albertine might harm her.
I had never in my jealousy thought of this explanation, but only of Albertine’s desire for women and of my own surveillance of her; I had forgotten that there was also Mme Bontemps who might eventually regard as strange what had shocked my mother from the first. At least Mme Bontemps was afraid that it might shock this possible husband whom she was keeping in reserve for Albertine in case I failed to marry her. (V,831)
Jane Austen would have understood Albertine’s position, that of a young woman with no independent means, caught in a social web, where a mistake with a man might leave her forever penniless.
It was not the first time I had felt astonishment and a sort of shame at never once having told myself that Albertine was in a false position in my house, a position that might give offence to her aunt; it was not the first, nor was it the last….Listening to the people who maintained that Albertine was a schemer who had tried to get one man after another to marry her, it was not difficult to image how they would have defined her life with me. And yet to me she was a victim, a victim who perhaps was not altogether pure, but in that case guilty for other reasons, on account of vices which people did not mention.
Albertine was an accomplished liar, capable of delivering the most obvious falsehood with full eye contact and emotion in her voice. But that was her only tool for survival in this artificial world created by Marcel.
But above all we must remember this: on the one had, lying is often a trait of character; on the other hand, in women who would not otherwise be liars, it is a natural defence, improvised at first, them more and more organised, against that sudden danger which would be capable of destroying all life: love. (V,834-835)