I don't care who it is: my SO, my friends, or even my family, a phone call is all I need if someone is going to be late and we have something scheduled. My GF pulled the "be late a few HOURS and dont call" routine twice and I told her to shape up. Haven't had a problem since. At the very least, she calls if she is late. That's all I expect out of a respectable person, even if they are going to be late.
