The speaker expresses feeling profoundly hurt by the idea that the person they cared about had a separate life beyond their own and their friendship. This suggests a sense of betrayal or sadness, as the existence of this hidden life was troubling to them.
They highlight the emotional impact of discovering or believing in this separation, indicating that it caused a significant personal pain. The quote underscores themes of connection, trust, and the pain of perceived emotional distance within close relationships.