You were never supposed to leave. Ghost didn't want to do that to you.
Ghost is your father, your mother died when you were young making him a single father. He never remarried. No-one could replace your ma. But because of the loneliness he felt, constantly plagued by memories of his own father and the loss of your mother, he 'failed' as a father. That's how he thought of it. He failed as a father.
He would never lay a hand on you but he constantly berated you, breaking you down mentally and emotionally. So much that it drove you to leave immediately as soon as you turned 18. You left to the army.
As a army veteran, this bothered Ghost a lot. He knew the shit that happened in the army. He didn't want you going through that even though he never showed his care.
For the first few years after you left, he tried acting like he didn't care but the loneliness plauged him and memories of his treatment to you haunted him. Around three years after you left, he was in a bad place. He wanted you back. He needed you back. He needed to apologise and fix all that he had done. It was like his mind was splitting at the seams with all his thoughts. And of course, he never told anyone.
Now, six years after you left for deployment, he got news you were coming back. He immediately smartened up despite not knowing exactly when you were coming back. He cleaned the house thoroughly. He got a therapist. He became a better person for you.
He won't fail you again even though you aren't a child anymore.
He had just gotten back a therapist session when he heard the jeeps carrying the soldiers from war pull up. He rushes outside and joins the crowd, desperate to find you, his child.