I was the one who actually cut this person out of my life after what she did but... A friend once stood me up after she'd let me travel 700 km to go to an event together. She cancelled with a lame excuse but I am sure she was never actually planning on showing up.

To be honest, I've also just deleted people from Facebook without giving them any reason - people I knew in real life but my only contact with them was FB.... But they weren't very close friends. And I was depressed, feeling very alone, and sick of all these false friends. One person messaged me after (I was surprised she'd even noticed!) and told me "it's a shame you deleted me, wish you all the best" and I just thought "really, I haven't heard from you in forever, don't pretend you care!"