House Husband? Try Supreme Immortal

What Logan Bale wanted was the three years finished. He had given them to his disciple, who was dying and asked him to look after the family, and a thousand years of living had not taught Logan how to break a promise. The promise came with a marriage. He took the disciple's granddaughter as his wife and lived in her family's house, where everyone treated him as something they had been saddled with. He took the slights and the obstruction without complaint and let the time run out. At the end of the three years he went. The family ran into one crisis after another once he was gone, and the woman he had married learned that the man in the house had been a physician other doctors spoke of as their forebear.