Bobby

"Bobby," I muttered.
Silence.
"Bobby, why aren't you leaving?" I asked.
Silence.
I started crying. I cried for how long, I do not know. After some time, I wiped my tears with my hands.
"You know," I said, "I know that you would not like to leave. It was just me assuming that someday you would. But still, you wouldn't. So maybe the right question would be- Bobby, why are you still here?"
Silence.
I laughed. Then, I started weeping again. "You were once out of my life," I told him, "But look at you now. Look at you now, huh?"
I laughed once again with my tears still coming out of my eyes. I can't understand how could I manage doing such thing. Somehow, I started to think that something is wrong with me.
"Bobby," I cried, "I never wanted you to materialize in front of me, just like now. What do you think would I do to make you go away? Please, just get away from me. Please, just stop touching me."
Silence.
"I tried to get rid of you many times already but you are always coming back. I stabbed you to death already. I had shot you with a gun, slashed your throat, hanged you, buried you alive, burned you to hell and so on. But still, you are here."
Silence.
"Tell me, what else should I do to get rid of you?."
Still silence.
I let out a deep sigh.
"Hey, get up from there. What are you doing?" said someone who tapped me from behind. I turned around and saw my mother. "It's time to take your medicines," she reminded me.
"But Mom, I'm still talking to Bobby," I complained. My mother smiled slightly at me.
"That's a wall dear you are talking to."
I turned around to see but still, it is Bobby. He is staring at me.

If killing Bobby would not make him disappear, why kill him again?
Define INSANITY. Expecting a different ending, yet doing the same thing..  over and over again.