"In the book the relationship with Katharine and Almasy is sort of only in the patient's mind"

The quote by Michael Ondaatje is referring to the relationship between Katharine and Almasy in his book. It recommends that the relationship in between the two characters is not a physical one, however rather a psychological one. It implies that the relationship is only in the mind of Almasy, the patient, and not in the real world. This might be translated as a metaphor for how Almasy is handling his own feelings and feelings. He is unable to reveal his feelings for Katharine in the physical world, so he instead creates a psychological relationship with her. This quote could likewise be interpreted as a commentary on the power of imagination and how it can be utilized to develop relationships and feelings that might not exist in the real world. It is a pointer that our thoughts and sensations can be simply as effective as physical relationships.