I don't know which edition you're referring to. I suppose the lines 43-58 are actually the third paragraph. So, here's the answer:
The narrator's relationship with her husband has changed because of a supernatural influence that she can't exactly explain or fathom. She doesn't really know what happened, when, or why, but at night her husband was not the same person she married. "It’s the moon’s fault, and the blood. It was in his father’s blood," she reasons. Her husband is alienated because of this, and somehow she feels that they don't belong together anymore. He goes out to find those who are like him. "Something comes over the one that’s got the curse in his blood, they say, and he gets up because he can’t sleep, and goes out into the glaring sun, and goes off all alone — drawn to find those like him."
Answer:
"He held up his right hand and spread his fingers out in a fan. I held up my left hand and spread my fingers out in a fan and we made our fingers and thumbs touch each other." (Christopher Boone, Chapter 31, p. 16)
Explanation:
