In my mind, there is this unassuming looking little switch, like you would see in a fuse box. It is labeled 'done with you'. When it gets flipped by someone, for what ever reason, I am Done With Them. I.E. I'll more than likely never talk to them again. I won't say bad things about them or anything (that just isn't my nature) but I will never deal with them again if I have any choice in the matter.
It is weird. As I look back at my life the switch has always been there, I just haven't really noticed it until recently. Maybe because it has a much larger hair trigger than it used to. But man, I am a lot more willing to completely cut someone out of my world then I used to be.
Maybe it is because I have less time.