I think this song is about someone who has been in some bad relationships before that didn't work out so she just decided to give up on love. Once some time goes by it gets easier and easier to live without love, you just get used to it. Before you know it your frozen. Then she met someone who she fell in love with but the people who know her don't want to her to get hurt again so they are telling her to be careful and reminding her about how people are so she doesn't let herself fall in love so fast. But once you're heart's been "frozen" for so much time falling in love feels so great, like its been brought back to life, ripped open and just pouring out love. I think what she is saying is that she can't help it, she's already in love with him. Hes already gotten to her heart and no matter what now she's going to be in love with him, weather its a good idea or not.