Claire is portrayed as being distant from her husband, Stuart. Though married to each other, they might as well be strangers, so remote are they from each other emotionally. As the story unfolds, it becomes painfully obvious that she no longer really understands her husband. She simply cannot understand why he and his buddies carried on with their fishing instead of reporting the dead girl's body to the police straight away.
But at the same time, Claire doesn't seem to understand herself anymore. She's identified herself so much with the dead girl, that her own identity has become somewhat obscured. We sense that perhaps Claire's whole identity is so bound up with her marriage, that when that marriage starts hitting the rocks, it's inevitable that she no longer really knows who she is. Claire seems to realize this herself, which is why she attends the young girl's funeral even though she never knew her. Claire is slowly but surely turning away from the identity imposed upon her by a marriage in which she no longer believes.