She is telling that she is feeling guilty

We were Best friends. She had break up with her boyfriend. We came close in December. Slowly she began to hold my hands, kiss on my cheeks. She was so comfortable & happy. Even we hugged & kissed. Now she is telling that she is not doing right with hr ex. She tells me that I am the BEST BOYFRIEND in the world, but don't want to get into a relationship now, even when she doesn't know. I can't wait anymore. I've loved her. I want her as my sweet cute girlfriend as she was. What should I do?