The character reflects on a past experience of profound emotional pain, which he associates with the vulnerability that comes from loving another person. This memory of heartache is so intense that he resolves never to open himself up to the possibility of love again, especially for humans. It illustrates the fear of getting hurt that can often accompany deep emotional connections.
This moment highlights the internal struggle of wanting to love while being haunted by past traumas. The decision to avoid love is a protective measure against the suffering that can arise from it. It underscores a common theme in literature where characters grapple with the potential for pain that love brings, weighing it against the need for connection and intimacy.