What makes Jack feel caught in an ugly middle position?

Explanation

Jack feels that he has been caught in an ugly middle position physically, emotionally as well as mentally. The woodwork, a cage of moldings and rails and skirting boards all around them was half old tan and half new ivory.
He was conscious of his duties as a father and as a husband. Little Bobby was already asleep. His efforts to make Jo fall asleep proved quite fatiguing. She kept on interrupting him, asking for clarifications, pointing errors and suggesting alternatives.
Jack did not like that women should take anything for granted. He liked them to be apprehensive. So he extended the story, though he was in a haste to go down stairs and help his pregnant wife in her hard work of painting the woodwork. The result of the extension to the story proved unfruitful and unpleasant for Jo, Jack and Clare. Jo wanted him to change the ending of the story. Clare complained that he had told a long story. Jack felt utter weariness and did not want to speak with his wife or work with her or touch her. He was
really caught in a ugly middle position as he could not wipe out the gap between the old and the young generation.