This comes up in the course of a LOT of other discussions about this movie and people seem to have trouble understanding how it could POSSIBLY have happened, so I thought it might be handy to just give these points a quick once-over and some discussion in their own thread. Mikaela dumping Sam IS perfectly within the bounds of her character. As we saw with Mikaela and Trent in the first film, she DOES NOT tolerate jerks for very long. And as we saw with Sam in the second movie AND in this movie, he was clearly becoming a bit of a jerk. BAM. </3 Simple as that. Hell, just think back to the second movie and start counting the number of times she tries to break up with him, lol. Furthermore, Carly says things like, "God, your temper tantrums are SO sexy" and seems to mean it, suggesting the profile of a woman who likes her men a bit controlling and manipulative. A point which also just so happens to explain how Dylan was able to "steal her away" to work for him AS WELL AS explaining broadly her former career in politics, if you think about it. Just like Sam told his Mom about Carly, she really DOES "love him for who he is" -- temper tantrums and all -- unlike Mikaela. And there you have it.