The text message that ended it all

Sarah: I know what I'm getting you for your birthday and if you don't love it, then you're an idiot :)
Mark: Why do you say things like that? It's mean.
Sarah: I wasn't saying it to be mean, I just meant that it's foolproof. Forgive me? That's why I also included the :). Please don't get mad over it.
Mark: It was uncalled for.
Sarah: I'm sorry. It was a bad choice of words. I would take it back if I could.
Mark: I can't do this anymore.