Final answer:
The narrator's father married late in life, but the specific reason is not stated. He met his bride-to-be while searching among some papers.
Step-by-step explanation:
The reason why the narrator's father married late in life is not explicitly stated in the given information. However, based on the passage 'Turning to the regal-looking woman lounging before the fire', it can be inferred that the narrator's father met his bride-to-be while he was searching among some papers. The passage does not mention the name or any specific details about the person whom he married.