Just When You Really Need Someone (slight spoiler)...

They abandon you: that seems to be the message of this film. It's a tough film, where the boy just has to learn to deal with being shunted around. If it was made in America they would have ended with more hope: even Poil De Carrotte, the other great movie of child abandonment, ended with a reconciliation.

The abandonment isn't even deliberate, just a typical piece of thoughtlessness: but as Philip Larkin says, most things are never meant.