Henry was certainly not leaving his father's house for ever, but merely going into lodgings with a friend, with full privileges to visit his own home as often as he chose.
Still, he was, all the same, leaving home, and he was the first to leave it.

The mother, at all events, knew that this was the beginning of the end, knew that, with her first-born's departure (desertion, she may have called it), a new era had commenced for the home,--the era of disintegration.

For twenty years and more it had been all building and building; now it would be all just pulling down again; and there was a dreary sound as of demolition and wind-driven rain in her ears.
Oh, tragic love of mothers! Of no love is the final loss and doom so inevitably destined.

The husband may desert the wife, but the son is sure to desert his mother--must, for nature demands the desertion.

Put not your trust in princes--and yet put it rather in princes, oh, fond and doting parents, than in the blue-eyed flower of childhood for which year after year, with labours infinite, you would buy all the sunshine of the world.
Henry's pang at leaving home was mainly the pang of parting with his mother.