One of the clearest sections of this incredibly moving short story where the narrator clearly expresses regret about the choices she has made in life, relating to what she did or didn't do, comes when she talks about her daughter, Lucy, and how now she is part of the culture of her husband and is therefore, in part, lost to her. Note the following quote:
But then she was born here. And now she belongs. If I had taken her away then, when she was eight months old, she would have belonged with me.
The biggest single regret that the narrator has is that she did not return to the UK with her daughter when the problems with her husband first started happening. Now, it is too late, and she is left stranded in a world where she does not belong and where she does not want to be, but is forced to remain in because her daughter now belongs there in a way that the narrator, her mother, will never belong.