Can i add a person, girlfriend or fiancée or their children as a dependent if you've helped them by paying living expenses & other expenses?

My girlfriend lives in another state & needed help with living conditions. shi's had t move 3 times due to family issues & medical issues. She now lives in a apartment. I plan on moving on moving there soon.  I've been paying my living conditions as well as hers the best i could to keep both places running. till conditions are best for me to move there. As i'm trying to transfer my job closer there.