Phone calls

So I had a mate call me up, after I promised her I would be doing the actual calling up. She pipped me to the post as it were. She was telling me about her day and every wanky thing in between.

"My I do seem to own a kick ass phone"

FRIEND: So, then I said this to him, he then said this thinkfkjdgfdjgvkjd, blah blah blah

ME: Yeah, uh huh........ok.........exactly. Wow, uh huh, yeah totally..

FRIEND: Then omg she said that thing with the other thing BLAH BLAH BLAH

ME: Is that so? cool.....yeah....ETC

This is a normal conversation, with me providing my ears for someone's drivel. So why does it sting when she gets a call from someone else and promptly hangs up on me?