What the hell was that?!

A couple of years ago a strange thing happened in my student house that I still cannot explain.

One summer night as I was sleeping soundly I suddenly woke up. A night lamp was on and as I tried to dose off I looked at my two rabbits who were standing so still they looked like statues and as if their heads were facing the window. I turned my head towards the window, my eyes went weirdly blurry as I saw something poking between the blinds and then suddenly a big circular head appeared with black perfectly circular eyes. I couldn't concentrate properly and see what exactly it was. I shouted at my boyfriend at the time and he jumped off the bed, went straight to the window and saw absolutely nothing, no traces of intruders etc as he rushed literally milliseconds as I shouted to him.

In the morning we just saw traces of moved rocks on the ground around that window but nothing too out of the ordinary.

Any ideas what this could have been. It still haunts me to this day!