Is the son's absence and his continuous communication with his mother considered a cause for her sadness and sorrow over his separation?

Most scholars hold the view that a child may travel for trade or similar purposes without the permission of their parents, provided that the travel or stay does not pose a danger, and provided that there is no fear that the parents will suffer loss in their absence. Thus, for travel related to trade or Hajj, parental permission is not required because there is no fear of harm, unlike in the case of jihad or dangerous journeys. Therefore, your travel to seek sustenance and your visits to your mother, as well as maintaining contact with them, are permissible matters.