How much do we know or understand people around us and why is it it seems like a never ending quest to get to know as much as possible about the people we like ? I think for example about the common thing among friends that one is telling others about how the other person thinks or feels "oh i know Sven always likes when we talk about food, don't you Sven" or "me and Sven always love to do this and that" as a means of telling the others how "close" they are.
Try to image this - all You ever can see of or understand about someone else is an image fitting a surface like that of a looking glass (Actually You only understand the space between You and the glass but let's leave that for now) The person will display bits and pieces of him/herself on this glass and the more you are offered the closer You will feel, it can be quite intoxicating being presented these images by a generous person - makes You feel very special and chosen.
The closer You get to the looking glass the bigger is the angle of perspective showing You the personality of the person inside (still Your perspective is bound to be controlled by what is displayed by the person on the "inside") Being given this bigger perspective is a loving gesture and the one sharing it might feel it's a bit "dangerous" to show bigger pieces of the inner self openly exposed like that, in fact I can imagine this being a substantial part of the give and take dance of love ...
The feeling of having "control" over (or being able to reduce) the space between You and a person is comforting as this seems to minimize misconceptions etc. The distance is a threat ... This might be why we constantly strive to get closer - to feel more confident in our own sphere, to feel safe.
There is a point of this "thought" : 1) What we feel as "knowing somebody" is actually only us somewhat controlling the space between two persons and 2) what we perceive as someones personality is no more than an image chosen to be presented by this person on the "looking glass" surface - NOT the true personality of that person.
