Hellos and goodbyes are part of life. People are part of your life for a reason, for a season and for a lifetime.
He was part of my life for a reason: to teach me not to be too trusting, and to be objective about giving instructions and being transparent about work outputs.
They are part of my life for a season, there to learn from one another, borne out of need not unsatisfied but there comes a point for farewells because we need to follow our heart's desires and go where God leads...
Those who stay are there for a lifetime, to provide comfort, to witness one's life journey and to share the milestones.