My girlfriend has to be convinced that im there for her when she's getting teary eyed over her grandaughter, t?

Some women just feel that nobody gets what they are going through, and there really is no explanation for it. You should try giving her a little space maybe. I understand that you want to make her feel better, but I think the only way you can do that is to try and keep her mind off of whatever is making her feel sad. As long as you tried to make her feel better, there's nothing you can do but back off a little bit until she feels comfortable and ready to talk about her situation directly. I hope your girlfriend feels better!