This girl has liked me for months, and recently I have started liking her. She had a bad day so in an attempt to cheer her up I told her that I liked her but after she told me it's complicated. She was quite reluctant to tell me how she felt and what was wrong and as far as I know, always has been.

Then you don't get serious, or carried away, until you do know why its complicated.

In other words, she's complicated.