Girl i've never met in my dreams

That's the wonderful thing about imagination. Anything you want you can have in your dreams.

Look her up on Facebook

Mae could be somebody you have seen from a distance in your daily life and never got close enough to talk to. Our subconscious minds see a lot of stuff that we are not aware of. She could be somebody you would like to meet and get to know, and your subconscious mind is telling you that in your dreams. I suggest you look around more carefully when out in public and pay closer attention to people around you, especially people out at the edge of your personal space. You might actually recognize the girl from your dreams. Something similar to this happened to a lady friend of mine, except the guy she repeatedly saw in her dreams was a violent predator. When she finally encountered him in real life she discovered that he had been stalking her. She had never really seen him consciously but her subconscious mind had seen him and sensed that he was a threat and was trying to warn her.

Maybe she's a ghost?

I once read an article on dream facts. Apparently, you've met/know a person if you dream about them.

Something similar to what you're describing has happened to me before. For years, I dreamed about this woman, who I could swear I didn't remember meeting or seeing prior. Then one night, we ended up seeing each other in person. Perhaps one day, you'll end up meeting this "Mae". :)