What does this mean? (My first girl problem)

The first thing I have to ask, and I mean no offense here, is how old are you?
I get the impression you are still in high school, in which case it is most definitely not your fault. High school girls are notorious for changing their mind every two seconds and never knowing what they want. It's the very reason why some of them literally have a new boyfriend every week.

Even if you aren't in high school though, depending on how mature the girl is this could still be that case. A lesson you can take from all this, is that some women just can't make up their goddamn minds. My wife, for example, can't even decide most of the time where she wants to go out to eat. This usually leads to about 15 minutes of "Honey where do you want to go eat?", "I don't know where do you want to go to eat?"...lather, rinse, repeat.

Either way, don't worry about it too much. It sounds like she just made up an excuse because she wanted out. Ignore her the same way she does you and go find you another woman.

Jam it back in, in the dark.