She met a guy she had very strong feelings for, but he didn't necessarily feel the same way. He always went out at night without her, but she loved him, so she felt that it was ok. But when he had proposed to "leave to start his life over" (possibly a way to leave Lana for good because he never really loved her), and did so, Lana had begged him to stay. But he had left her only to cope with her feeling of loneliness. She was in denial and felt that he still loved her as much as she loved him, so when he said he would come back to her the next day, she had waited up all night. But he never came, and Lana feels that the people he had been with to make "a living" had drawn him in to the point that he couldn't leave, even if he had tried, and that he really wanted to come back to her. She could've also believed that he just needed time to remember how much they had a loving relationship, therefore she "would wait a million years".