Also I'm gonna add an example to this.
It's not like I strive to be less friendly. Its just that I'm more inclined to since I don't really know sed person at all other then they do something which pisses me off.
Say you are driving down the road and your friend cuts you off. It may piss you off a bit but hey, its your friend, you will forgive them.
Now, keep that same scenario but make it some random person who cut you off. Suddenly this guy is now the epitome or annoyance.
Point is, since you have memories with your friend you forget them cutting you off, but since you've never met the random driver the only memory you have of them is making you drive up onto the sidewalk. Hence making you more hostile towards them.