Thanks for asking your question! I'm sorry to hear about your tax issue and I'm going to try my best to help you understand or resolve it.
You can claim your girlfriend as a dependent if she lived with you the entire year, is a US citizen or citizen of Canada or Mexico, if she made less than $3,800 during the year, and you provided more than 1/2 of her total support. She also cannot file a joint return with anyone and cannot be claimed as a dependent on someone else's return.
If she meets those criteria, you can claim her on your taxes.
Thanks, Jack. Please let me know if you need anything additional. If not, please rate my response "excellent" so that I may receive credit for assisting you today. Thanks again.