I think this song is about being constantly disappointed by love, but continuing to risk everything to try to find it. She is saying that despite her better judgement she is going to take a chance on this new person she has acquired feelings for, but she is once again disappointed. She's been dating around since she was 14 and it's still the same old thing after all this time, after becoming an adult, nothing is changing, she is still continuing to experience disappointment after disappointment.
I think this song is about being constantly disappointed by love, but continuing to risk everything to try to find it. She is saying that despite her better judgement she is going to take a chance on this new person she has acquired feelings for, but she is once again disappointed. She's been dating around since she was 14 and it's still the same old thing after all this time, after becoming an adult, nothing is changing, she is still continuing to experience disappointment after disappointment.