Here is a trick I learned that worked for me:
Be having a normal conversation and say something subtle like:
"I love labels, they make relationships, things in general so much easier in life. They make it so much easier to know where you stand with someone in your life"
This does two things, it tells her that you like labels (IE - Boyfriend / Girlfriend.) But it also lets you keep your power and not give it away by doing something wussyish and asking her, "Will you be my girlfriend?"
If you say the remark about labels and knowing where you stand, and she bites, the conversation will probably lead the way of where you stand in the current relationship. Just remember, don't ask her to be your girlfriend. If anything tell her casually, "I guess you are my girlfriend." Like you are doing her the favor here.
Here is a tip for the conversation:
Sometimes these conversations can lead to a place where she fires a question to you like, "Where do you think we stand?" To which point you can follow up with some ****y and funny remark like, "You love me, but I'm still playing hard to get." Then finish it off with a sly smile. Then kiss her.
If all else fails, just introduce her to your friends or someone you know as your girlfriend. I think she will get the hint that way.
Good luck and great question!
