How do I politely tell her I care?

Tell her this, "Are you okay? What's wrong? Please tell me because it might not seem like it, but I really care." She might tell you. But it takes a girl time to let it out about her personal life. Tell her that you understand if she doesn't want to talk about it. But if she tells you, don't talk about your past expereinces or anything. Listen to her. If you like her and maybe want to date her, listen. Listening is the key to showing someone that you care about their problems. Good luck! Hope I helped!