Katy is pissed at her boyfriend becuase he can never decide on anything what so ever. So she figures well if you can't decide on anything then whole do you know if you truley like me at all. She knows that he won't change and it's time too go.
But I like this song too. It's really fun and Katy shows off her vocals. Hopefully people will move past the "I Kissed A Girl", which has nothing wrong with it, to see her true musical talent.