Knock and run

Some one knocks on the door.
You, having learnt that knocking on the door is often associated with uncomfortable news ignore the first few knocks.
Despite so, the knocks continue.
You have no choice but to approach the door, hoping with each step that the person on the other side will give up and walk away...but they dont.
You stand at the side of the door and cautiously ask "who's there?"
And a nervous, yet determined voice introduces themself to you, asking you to open the door for them.
You hesitate.
Then with some effort you manage to creak the door open slightly so you can peek over and see the knocker, personally.
He is standing there, with friendly eyes and a smile that is so welcoming. The stranger reaches out their hand and asks to come in. They tell you to take your time and to think carefully and they dont mind waiting out there just a little until you trust them enough to let them in.
After some thought and emotional negotiations within yourself you decide to let this stranger come in.
I can trust this person, I hope. I think this might be safe and worth it.
You cautiously open the door gradually until it is wide enough to let them in.
You see the person at the door face to face and it dawns on both of you that both sides had made the right decision. He was glad he summoned up the courage to knock and she was glad she summoned up the confidence to let this warm stranger in.
"Come in", you say "It's pretty cold outside, it'll be nicer here"
The stranger smiles with delicate wrinkles around his eyes and just as he is about to step in exclaims "Oh, I dont think I can." and he walks away just as abruptly as he has come.
You stand at the door, dumbfounded.
Why? What happened? Did I do something wrong? Why did they leave just as I opened up the door?
After I had put in that much thought and consideration into the topic, the stranger that I (sort of) trusted walks away!
After overcoming the speechless shock, a shade of anger rises up within you and you slam the door shut. Who is he to do this to me? It's totally my fault for opening that damn door! Without even an apology or a word of consideration! Despicable!
The echos of the slamming of the door reverberate in your ears and after the anger calms down another thought crosses your mind...what if they come back at the door? Will I open it again? Or will I keep it shut?
You are filled with this curiosity that conflicts a bit with your ego and you dont know what you would do. You creep over to the peephole every now and again to see if they've returned. And surely, there is no one.
It is a curious thing indeed.
He should have never knocked in the first place...