Dad was more than slightly eccentric, as well as a decade older than VK's mum, who had him when she was about twenty-ish. I think he took refuge in the library because it meant The Wife couldn't find him or at least, she assumed he was doing important things. She was quite the ferocious battleaxe, running the household with a rod of iron.

(And Johannes just murmured that he crept into the library to hide after getting caught filching food in the kitchen and found dad who was supposably working. He was asleep in a big, comfy chair and looked quite at ease. VK thought his father was a genius ;))